1
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Peng K, Li W, Sun M, Rivero JDH, Ti C, Han X, Ge L, Yang L, Zhang X, Bao W. Topological valley Hall polariton condensation. NATURE NANOTECHNOLOGY 2024; 19:1283-1289. [PMID: 38789618 DOI: 10.1038/s41565-024-01674-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 04/10/2024] [Indexed: 05/26/2024]
Abstract
A photonic topological insulator features robust directional propagation and immunity to defect perturbations of the edge/surface state. Exciton-polaritons, that is, the hybrid quasiparticles of excitons and photons in semiconductor microcavities, have been proposed as a tunable nonlinear platform for emulating topological phenomena. However, mainly due to excitonic material limitations, experimental observations so far have not been able to enter the nonlinear condensation regime or only show localized condensation in one dimension. Here we show a topological propagating edge state with polariton condensation at room temperature and without any external magnetic field. We overcome material limitations by using excitonic CsPbCl3 halide perovskites with a valley Hall lattice design. The polariton lattice features a large bandgap of 18.8 meV and exhibits strong nonlinear polariton condensation with clear long-range spatial coherence across the critical pumping density. The geometric parameters and material composition of our nonlinear many-body photonic system platform can in principle be tailored to study topological phenomena of other interquasiparticle interactions.
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Affiliation(s)
- Kai Peng
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Nanoscale Science and Engineering Center, University of California, Berkeley, Berkeley, CA, USA
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Wei Li
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Meng Sun
- School of Physics and Optoelectronic Engineering, Beijing University of Technology, Beijing, China
| | - Jose D H Rivero
- Department of Physics and Astronomy, College of Staten Island, CUNY, New York, NY, USA
- The Graduate Center, CUNY, New York, NY, USA
| | - Chaoyang Ti
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Xu Han
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USA
| | - Li Ge
- Department of Physics and Astronomy, College of Staten Island, CUNY, New York, NY, USA
- The Graduate Center, CUNY, New York, NY, USA
| | - Lan Yang
- Department of Electrical and Systems Engineering, Washington University, St Louis, MO, USA
| | - Xiang Zhang
- Nanoscale Science and Engineering Center, University of California, Berkeley, Berkeley, CA, USA.
| | - Wei Bao
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA.
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, USA.
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2
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Shan ZL, Sun YK, Tao R, Chen QD, Tian ZN, Zhang XL. Non-Abelian Holonomy in Degenerate Non-Hermitian Systems. PHYSICAL REVIEW LETTERS 2024; 133:053802. [PMID: 39159106 DOI: 10.1103/physrevlett.133.053802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 06/01/2024] [Accepted: 07/10/2024] [Indexed: 08/21/2024]
Abstract
Non-Abelian holonomy, a noncommutative process that measures the parallel transport of non-Abelian gauge fields, has so far been realized in degenerate Hermitian systems with degenerate eigenstates or nondegenerate non-Hermitian systems with exceptional points. Here, we introduce non-Abelian holonomy into degenerate non-Hermitian systems possessing degenerate exceptional points and degenerate energy topologies. The interplay between energy degeneracy and energy topology around exceptional points leads to a non-Abelian holonomy with multiple energy levels and multiple degenerate levels simultaneously, going beyond that in degenerate Hermitian systems with a single energy level, or in nondegenerate non-Hermitian systems with a single degenerate level. We exploit an on-chip photonic platform to experimentally demonstrate the holonomy induced non-Abelian phenomenon, including the switching of eigenstates associated with different degenerate exceptional points and sequence-dependent holonomic outcomes. Our work shifts the paradigm of non-Abelian holonomy and adds new degrees of freedom for non-Abelian applications.
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Affiliation(s)
- Zhong-Lei Shan
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yi-Ke Sun
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Ran Tao
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Qi-Dai Chen
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Zhen-Nan Tian
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Xu-Lin Zhang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
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3
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Yang Y, Yang B, Ma G, Li J, Zhang S, Chan CT. Non-Abelian physics in light and sound. Science 2024; 383:eadf9621. [PMID: 38386745 DOI: 10.1126/science.adf9621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 01/17/2024] [Indexed: 02/24/2024]
Abstract
Non-Abelian phenomena arise when the sequence of operations on physical systems influences their behaviors. By possessing internal degrees of freedom such as polarization, light and sound can be subjected to various manipulations, including constituent materials, structured environments, and tailored source conditions. These manipulations enable the creation of a great variety of Hamiltonians, through which rich non-Abelian phenomena can be explored and observed. Recent developments have constituted a versatile testbed for exploring non-Abelian physics at the intersection of atomic, molecular, and optical physics; condensed matter physics; and mathematical physics. These fundamental endeavors could enable photonic and acoustic devices with multiplexing functionalities. Our review aims to provide a timely and comprehensive account of this emerging topic. Starting from the foundation of matrix-valued geometric phases, we address non-Abelian topological charges, non-Abelian gauge fields, non-Abelian braiding, non-Hermitian non-Abelian phenomena, and their realizations with photonics and acoustics and conclude with future prospects.
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Affiliation(s)
- Yi Yang
- Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong, China
- HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Biao Yang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, China
- Hunan Provincial Key Laboratory of Novel Nano-Optoelectronic Information Materials and Devices, National University of Defense Technology, Changsha, China
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha, China
| | - Guancong Ma
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Jensen Li
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Shuang Zhang
- Department of Physics, The University of Hong Kong, Pokfulam, Hong Kong, China
- HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
- New Cornerstone Science Laboratory, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - C T Chan
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
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4
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Bai K, Liu TR, Fang L, Li JZ, Lin C, Wan D, Xiao M. Observation of Nonlinear Exceptional Points with a Complete Basis in Dynamics. PHYSICAL REVIEW LETTERS 2024; 132:073802. [PMID: 38427883 DOI: 10.1103/physrevlett.132.073802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 01/12/2024] [Indexed: 03/03/2024]
Abstract
The exotic physics associated with exceptional points (EPs) is always under the scrutiny of theoretical and experimental science. Recently, considerable effort has been invested in the combination of nonlinearity and non-Hermiticity. The concept of nonlinear EPs (NEPs) has been introduced, which can avoid the loss of completeness of the eigenbasis in dynamics while retaining the key features of linear EPs. Here, we present the first direct experimental demonstration of a NEP based on two non-Hermition coupled circuit resonators combined with a nonlinear saturable gain. At the NEP, the response of the eigenfrequency to perturbations demonstrates a third-order root law and the eigenbasis of the Hamiltonian governing the system dynamics is still complete. Our results bring this counterintuitive aspect of the NEP to light and possibly open new avenues for applications.
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Affiliation(s)
- Kai Bai
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Tian-Rui Liu
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Liang Fang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jia-Zheng Li
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Chen Lin
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Duanduan Wan
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Meng Xiao
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Wuhan Institute of Quantum Technology, Wuhan 430206, China
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5
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Zhang XX, Nagaosa N. Topological spin textures in electronic non-Hermitian systems. Sci Bull (Beijing) 2024; 69:325-333. [PMID: 38129237 DOI: 10.1016/j.scib.2023.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/17/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023]
Abstract
Non-Hermitian systems have been discussed mostly in the context of open systems and nonequilibrium. Recent experimental progress is much from optical, cold-atomic, and classical platforms due to the vast tunability and clear identification of observables. However, their counterpart in solid-state electronic systems in equilibrium remains unmasked although highly desired, where a variety of materials are available, calculations are solidly founded, and accurate spectroscopic techniques can be applied. We demonstrate that, in the surface state of a topological insulator with spin-dependent relaxation due to magnetic impurities, highly nontrivial topological soliton spin textures appear in momentum space. Such spin-channel phenomena are delicately related to the type of non-Hermiticity and correctly reveal the most robust non-Hermitian features detectable spectroscopically. Moreover, the distinct topological soliton objects can be deformed to each other, mediated by topological transitions driven by tuning across a critical direction of doped magnetism. These results not only open a solid-state avenue to exotic spin patterns via spin- and angle-resolved photoemission spectroscopy, but also inspire non-Hermitian dissipation engineering of spins in solids.
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Affiliation(s)
- Xiao-Xiao Zhang
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan.
| | - Naoto Nagaosa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan; Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
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6
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Pang Z, Wong BTT, Hu J, Yang Y. Synthetic Non-Abelian Gauge Fields for Non-Hermitian Systems. PHYSICAL REVIEW LETTERS 2024; 132:043804. [PMID: 38335358 DOI: 10.1103/physrevlett.132.043804] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 11/27/2023] [Indexed: 02/12/2024]
Abstract
Non-Abelian gauge fields are versatile tools for synthesizing topological phenomena, but have so far been mostly studied in Hermitian systems, where gauge flux has to be defined from a closed loop in order for vector potentials, whether Abelian or non-Abelian, to become physically meaningful. We show that this condition can be relaxed in non-Hermitian systems by proposing and studying a generalized Hatano-Nelson model with imbalanced non-Abelian hopping. Despite lacking gauge flux in one dimension, non-Abelian gauge fields create rich non-Hermitian topological consequences. With SU(2) gauge fields, the braiding degrees that can be achieved are twice the highest hopping order of a lattice model, indicating the utility of spinful freedom to attain high-order nontrivial braiding. At both ends of an open chain, non-Abelian gauge fields lead to the simultaneous presence of non-Hermitian skin modes, whose population can be effectively tuned near the exceptional points. Generalizing to two dimensions, the gauge invariance of Wilson loops can also break down in non-Hermitian lattices dressed with non-Abelian gauge fields. Toward realization, we present a concrete experimental proposal for non-Abelian gauge fields in non-Hermitian systems via the synthetic frequency dimension of a polarization-multiplexed fiber ring resonator.
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Affiliation(s)
- Zehai Pang
- Department of Physics and HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Bengy Tsz Tsun Wong
- Department of Physics and HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Jinbing Hu
- Department of Physics and HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
- College of Optical-Electrical Information and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Yi Yang
- Department of Physics and HK Institute of Quantum Science and Technology, The University of Hong Kong, Pokfulam, Hong Kong, China
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7
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Yang Z, Huang PS, Lin YT, Qin H, Zúñiga-Pérez J, Shi Y, Wang Z, Cheng X, Tang MC, Han S, Kanté B, Li B, Wu PC, Genevet P, Song Q. Creating pairs of exceptional points for arbitrary polarization control: asymmetric vectorial wavefront modulation. Nat Commun 2024; 15:232. [PMID: 38177166 PMCID: PMC10766979 DOI: 10.1038/s41467-023-44428-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 12/13/2023] [Indexed: 01/06/2024] Open
Abstract
Exceptional points (EPs) can achieve intriguing asymmetric control in non-Hermitian systems due to the degeneracy of eigenstates. Here, we present a general method that extends this specific asymmetric response of EP photonic systems to address any arbitrary fully-polarized light. By rotating the meta-structures at EP, Pancharatnam-Berry (PB) phase can be exclusively encoded on one of the circular polarization-conversion channels. To address any arbitrary wavefront, we superpose the optical signals originating from two orthogonally polarized -yet degenerate- EP eigenmodes. The construction of such orthogonal EP eigenstates pairs is achieved by applying mirror-symmetry to the nanostructure geometry flipping thereby the EP eigenmode handedness from left to right circular polarization. Non-Hermitian reflective PB metasurfaces designed using such EP superposition enable arbitrary, yet unidirectional, vectorial wavefront shaping devices. Our results open new avenues for topological wave control and illustrate the capabilities of topological photonics to distinctively operate on arbitrary polarization-state with enhanced performances.
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Affiliation(s)
- Zijin Yang
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
- School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
| | - Po-Sheng Huang
- Department of Photonics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Yu-Tsung Lin
- Department of Photonics, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Haoye Qin
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Jesús Zúñiga-Pérez
- Université Cote d'Azur, CNRS, CRHEA, Rue Bernard Gregory, Sophia Antipolis, 06560, Valbonne, France
- Majulab, International Research Laboratory IRL 3654, CNRS, Université Côte d'Azur, Sorbonne Université, National University of Singapore, Nanyang Technological University, Singapore, Singapore
| | - Yuzhi Shi
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Zhanshan Wang
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Xinbin Cheng
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Man-Chung Tang
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Sanyang Han
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Boubacar Kanté
- Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, 94720, USA
| | - Bo Li
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
- Suzhou Laboratory, Suzhou, 215123, China
| | - Pin Chieh Wu
- Department of Photonics, National Cheng Kung University, Tainan, 70101, Taiwan.
- Center for Quantum Frontiers of Research & Technology (QFort), National Cheng Kung University, Tainan, 70101, Taiwan.
- Meta-nanoPhotonics Center, National Cheng Kung University, Tainan, 70101, Taiwan.
| | - Patrice Genevet
- Université Cote d'Azur, CNRS, CRHEA, Rue Bernard Gregory, Sophia Antipolis, 06560, Valbonne, France.
- Physics Department, Colorado School of Mines, 1523 Illinois St., Golden, CO, 80401, USA.
| | - Qinghua Song
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
- Suzhou Laboratory, Suzhou, 215123, China.
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8
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Han PR, Wu F, Huang XJ, Wu HZ, Zou CL, Yi W, Zhang M, Li H, Xu K, Zheng D, Fan H, Wen J, Yang ZB, Zheng SB. Exceptional Entanglement Phenomena: Non-Hermiticity Meeting Nonclassicality. PHYSICAL REVIEW LETTERS 2023; 131:260201. [PMID: 38215365 DOI: 10.1103/physrevlett.131.260201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 11/15/2023] [Indexed: 01/14/2024]
Abstract
Non-Hermitian (NH) extension of quantum-mechanical Hamiltonians represents one of the most significant advancements in physics. During the past two decades, numerous captivating NH phenomena have been revealed and demonstrated, but all of which can appear in both quantum and classical systems. This leads to the fundamental question: what NH signature presents a radical departure from classical physics? The solution of this problem is indispensable for exploring genuine NH quantum mechanics, but remains experimentally untouched so far. Here, we resolve this basic issue by unveiling distinct exceptional entanglement phenomena, exemplified by an entanglement transition, occurring at the exceptional point of NH interacting quantum systems. We illustrate and demonstrate such purely quantum-mechanical NH effects with a naturally dissipative light-matter system, engineered in a circuit quantum electrodynamics architecture. Our results lay the foundation for studies of genuinely quantum-mechanical NH physics, signified by exceptional-point-enabled entanglement behaviors.
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Affiliation(s)
- Pei-Rong Han
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Fan Wu
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Xin-Jie Huang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Huai-Zhi Wu
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
| | - Chang-Ling Zou
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, Hefei 230088, China
| | - Wei Yi
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
- CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
- Hefei National Laboratory, Hefei 230088, China
| | - Mengzhen Zhang
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA
| | - Hekang Li
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Kai Xu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Hefei National Laboratory, Hefei 230088, China
| | - Dongning Zheng
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Hefei National Laboratory, Hefei 230088, China
| | - Heng Fan
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- Hefei National Laboratory, Hefei 230088, China
| | - Jianming Wen
- Department of Physics, Kennesaw State University, Marietta, Georgia 30060, USA
| | - Zhen-Biao Yang
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
- Hefei National Laboratory, Hefei 230088, China
| | - Shi-Biao Zheng
- Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, Fujian 350108, China
- Hefei National Laboratory, Hefei 230088, China
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9
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Zhou X, Ren X, Xiao D, Zhang J, Huang R, Li Z, Sun X, Wu X, Qiu CW, Nori F, Jing H. Higher-order singularities in phase-tracked electromechanical oscillators. Nat Commun 2023; 14:7944. [PMID: 38040766 PMCID: PMC10692225 DOI: 10.1038/s41467-023-43708-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 11/17/2023] [Indexed: 12/03/2023] Open
Abstract
Singularities ubiquitously exist in different fields and play a pivotal role in probing the fundamental laws of physics and developing highly sensitive sensors. Nevertheless, achieving higher-order (≥3) singularities, which exhibit superior performance, typically necessitates meticulous tuning of multiple (≥3) coupled degrees of freedom or additional introduction of nonlinear potential energies. Here we propose theoretically and confirm using mechanics experiments, the existence of an unexplored cusp singularity in the phase-tracked (PhT) steady states of a pair of coherently coupled mechanical modes without the need for multiple (≥3) coupled modes or nonlinear potential energies. By manipulating the PhT singularities in an electrostatically tunable micromechanical system, we demonstrate an enhanced cubic-root response to frequency perturbations. This study introduces a new phase-tracking method for studying interacting systems and sheds new light on building and engineering advanced singular devices with simple and well-controllable elements, with potential applications in precision metrology, portable nonreciprocal devices, and on-chip mechanical computing.
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Affiliation(s)
- Xin Zhou
- College of Intelligence Science and Technology, NUDT, 410073, Changsha, China.
| | - Xingjing Ren
- College of Intelligence Science and Technology, NUDT, 410073, Changsha, China
| | - Dingbang Xiao
- College of Intelligence Science and Technology, NUDT, 410073, Changsha, China
| | - Jianqi Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, 430071, Wuhan, China
| | - Ran Huang
- Center for Quantum Computing, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan
| | - Zhipeng Li
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Xiaopeng Sun
- College of Intelligence Science and Technology, NUDT, 410073, Changsha, China
| | - Xuezhong Wu
- College of Intelligence Science and Technology, NUDT, 410073, Changsha, China.
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Franco Nori
- Center for Quantum Computing, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109-1040, USA.
| | - Hui Jing
- Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, 410081, Changsha, China.
- Academy for Quantum Science and Technology, Zhengzhou University of Light Industry, 450002, Zhengzhou, China.
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10
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Wan T, Zhang K, Li J, Yang Z, Yang Z. Observation of the geometry-dependent skin effect and dynamical degeneracy splitting. Sci Bull (Beijing) 2023; 68:2330-2335. [PMID: 37741745 DOI: 10.1016/j.scib.2023.09.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/11/2023] [Accepted: 09/05/2023] [Indexed: 09/25/2023]
Abstract
The non-Hermitian skin effect is a distinctive phenomenon in non-Hermitian systems, which manifests as the anomalous localization of bulk states at the boundary. To understand the physical origin of the non-Hermitian skin effect, a bulk band characterization based on the dynamical degeneracy on an equal frequency contour is proposed, which reflects the strong anisotropy of the spectral function. In this paper, we report the experimental observation of a newly-discovered geometry-dependent non-Hermitian skin effect and dynamical degeneracy splitting in a two-dimensional acoustic crystal and reveal their remarkable correspondence by performing single-frequency excitation measurements. Our work not only provides a controllable experimental platform for studying the non-Hermitian physics, but also confirms the unique correspondence between the non-Hermitian skin effect and the dynamical degeneracy splitting, paving a new way to characterize the non-Hermitian skin effect.
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Affiliation(s)
- Tuo Wan
- School of Physics, Interdisciplinary Center for Quantum Information, Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China
| | - Kai Zhang
- Department of Physics, University of Michigan Ann Arbor, Ann Arbor 48105, USA
| | - Junkai Li
- School of Physics, Interdisciplinary Center for Quantum Information, Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China
| | - Zhesen Yang
- Department of Physics, Xiamen University, Xiamen 361005, China.
| | - Zhaoju Yang
- School of Physics, Interdisciplinary Center for Quantum Information, Zhejiang Province Key Laboratory of Quantum Technology and Device, Zhejiang University, Hangzhou 310027, China.
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11
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Sim K, Defenu N, Molignini P, Chitra R. Quantum Metric Unveils Defect Freezing in Non-Hermitian Systems. PHYSICAL REVIEW LETTERS 2023; 131:156501. [PMID: 37897761 DOI: 10.1103/physrevlett.131.156501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 05/25/2023] [Accepted: 08/22/2023] [Indexed: 10/30/2023]
Abstract
Non-Hermiticity in quantum Hamiltonians leads to nonunitary time evolution and possibly complex energy eigenvalues, which can lead to a rich phenomenology with no Hermitian counterpart. In this work, we study the dynamics of an exactly solvable non-Hermitian system, hosting both PT-symmetric and PT-broken modes subject to a linear quench. Employing a fully consistent framework, in which the Hilbert space is endowed with a nontrivial dynamical metric, we analyze the dynamics of the generated defects. In contrast to Hermitian systems, our study reveals that PT-broken time evolution leads to defect freezing and hence the violation of adiabaticity. This physics necessitates the so-called metric framework, as it is missed by the oft used approach of normalizing quantities by the time-dependent norm of the state. Our results are relevant for a wide class of experimental systems.
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Affiliation(s)
- Karin Sim
- Institute for Theoretical Physics, ETH Zürich, 8093 Zurich, Switzerland
| | - Nicolò Defenu
- Institute for Theoretical Physics, ETH Zürich, 8093 Zurich, Switzerland
| | - Paolo Molignini
- Cavendish Laboratory, University of Cambridge, 19 J J Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Department of Physics, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
| | - R Chitra
- Institute for Theoretical Physics, ETH Zürich, 8093 Zurich, Switzerland
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12
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Jiang H, Lee CH. Dimensional Transmutation from Non-Hermiticity. PHYSICAL REVIEW LETTERS 2023; 131:076401. [PMID: 37656848 DOI: 10.1103/physrevlett.131.076401] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 03/18/2023] [Accepted: 07/25/2023] [Indexed: 09/03/2023]
Abstract
Dimensionality plays a fundamental role in the classification of novel phases and their responses. In generic lattices of 2D and beyond, however, we found that non-Hermitian couplings do not merely distort the Brillouin zone (BZ), but can in fact alter its effective dimensionality. This is due to the fundamental noncommutativity of multidimensional non-Hermitian pumping, which obstructs the usual formation of a generalized complex BZ. As such, basis states are forced to assume "entangled" profiles that are orthogonal in a lower dimensional effective BZ, completely divorced from any vestige of lattice Bloch states unlike conventional skin states. Characterizing this reduced dimensionality is an emergent winding number intimately related to the homotopy of noncontractible spectral paths. We illustrate this dimensional transmutation through a 2D model whose topological zero modes are protected by a 1D, not 2D, topological invariant. Our findings can be readily demonstrated via the bulk properties of nonreciprocally coupled platforms such as circuit arrays, and provokes us to rethink the fundamental role of geometric obstruction in the dimensional classification of topological states.
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Affiliation(s)
- Hui Jiang
- Department of Physics, National University of Singapore, Singapore 117551, Republic of Singapore
| | - Ching Hua Lee
- Department of Physics, National University of Singapore, Singapore 117551, Republic of Singapore
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
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13
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Yu ZF, Xue JK. Photonic transistor based on a coupled-cavity system with polaritons. OPTICS EXPRESS 2023; 31:26276-26288. [PMID: 37710491 DOI: 10.1364/oe.492686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 07/17/2023] [Indexed: 09/16/2023]
Abstract
We investigate the transmission of probe fields in a coupled-cavity system with polaritons and propose a theoretical schema for realizing a polariton-based photonic transistor. When probe light passes through such a hybrid optomechanical device, its resonant point with Stokes or anti-Stokes scattered effects, intensity with amplification or attenuation effects, as well as group velocity with slow or fast light effects can be effectively controlled by another pump light. This controlling depends on the exciton-photon coupling and single-photon coupling. We also discover an asymmetric Fano resonance in transparency windows under the strong exciton-photon coupling, which is different from general symmetric optomechanically induced transparency. Our results open up exciting possibilities for designing photonic transistors, which may be useful for implementing polariton integrated circuits.
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14
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Zhang K, Fang C, Yang Z. Dynamical Degeneracy Splitting and Directional Invisibility in Non-Hermitian Systems. PHYSICAL REVIEW LETTERS 2023; 131:036402. [PMID: 37540867 DOI: 10.1103/physrevlett.131.036402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/28/2023] [Accepted: 06/21/2023] [Indexed: 08/06/2023]
Abstract
In this Letter, we introduce the concept of dynamical degeneracy splitting to describe the anisotropic decay behaviors in non-Hermitian systems. We demonstrate that systems with dynamical degeneracy splitting exhibit two distinctive features: (i) the system shows frequency-resolved non-Hermitian skin effect; (ii) Green's function exhibits anomalous behavior at given frequency, leading to uneven broadening in spectral function and anomalous scattering. As an application, we propose directional invisibility based on wave packet dynamics to investigate the geometry-dependent skin effect in higher dimensions. Our work elucidates a faithful correspondence between non-Hermitian skin effect and Green's function, offering a guiding principle for exploration of novel physical phenomena emerging from this effect.
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Affiliation(s)
- Kai Zhang
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Chen Fang
- Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Kavli Institute for Theoretical Sciences, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhesen Yang
- Kavli Institute for Theoretical Sciences, Chinese Academy of Sciences, Beijing 100190, China
- Department of Physics, Xiamen University, Xiamen 361005, Fujian Province, China
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15
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Li A, Wei H, Cotrufo M, Chen W, Mann S, Ni X, Xu B, Chen J, Wang J, Fan S, Qiu CW, Alù A, Chen L. Exceptional points and non-Hermitian photonics at the nanoscale. NATURE NANOTECHNOLOGY 2023; 18:706-720. [PMID: 37386141 DOI: 10.1038/s41565-023-01408-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 04/25/2023] [Indexed: 07/01/2023]
Abstract
Exceptional points (EPs) arising in non-Hermitian systems have led to a variety of intriguing wave phenomena, and have been attracting increased interest in various physical platforms. In this Review, we highlight the latest fundamental advances in the context of EPs in various nanoscale systems, and overview the theoretical progress related to EPs, including higher-order EPs, bulk Fermi arcs and Weyl exceptional rings. We peek into EP-associated emerging technologies, in particular focusing on the influence of noise for sensing near EPs, improving the efficiency in asymmetric transmission based on EPs, optical isolators in nonlinear EP systems and novel concepts to implement EPs in topological photonics. We also discuss the constraints and limitations of the applications relying on EPs, and offer parting thoughts about promising ways to tackle them for advanced nanophotonic applications.
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Affiliation(s)
- Aodong Li
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, China
| | - Heng Wei
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Michele Cotrufo
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
| | - Weijin Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Sander Mann
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
| | - Xiang Ni
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA
| | - Bingcong Xu
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, China
| | - Jianfeng Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jian Wang
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, China
| | - Shanhui Fan
- Department of Electrical Engineering, Ginzton Laboratory, Stanford University, Stanford, CA, USA
- Department of Applied Physics, Stanford University, Stanford, CA, USA
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA.
- Physics Program, Graduate Center, City University of New York, New York, NY, USA.
| | - Lin Chen
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, China.
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, China.
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16
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Bai K, Li JZ, Liu TR, Fang L, Wan D, Xiao M. Nonlinear Exceptional Points with a Complete Basis in Dynamics. PHYSICAL REVIEW LETTERS 2023; 130:266901. [PMID: 37450800 DOI: 10.1103/physrevlett.130.266901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 04/13/2023] [Accepted: 06/08/2023] [Indexed: 07/18/2023]
Abstract
Exceptional points (EPs) are special spectral singularities at which two or more eigenvalues, and their corresponding eigenvectors, coalesce and become identical. In conventional wisdom, the coalescence of eigenvectors inevitably leads to the loss of completeness of the eigenbasis. Here, we show that this scenario breaks down in general at nonlinear EPs (NEPs). As an example, we realize a fifth-order NEP (NEP_{5}) within only three coupled resonators with both a theoretical model and simulations in circuits. One stable and another four auxiliary steady eigenstates of the nonlinear Hamiltonian coalesce at the NEP_{5}, and the response of eigenfrequency to perturbations demonstrates a fifth-order root law. Intriguingly, the biorthogonal eigenbasis of the Hamiltonian governing the system dynamics is still complete, and this fact is corroborated by a finite Petermann factor instead of a divergent one at conventional EPs. Consequently, the amplification of noise, which diverges at other EPs, converges at our NEP_{5}. Our finding transforms the understanding of EPs and shows potential for miniaturizing various key applications operating near EPs.
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Affiliation(s)
- Kai Bai
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Jia-Zheng Li
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Tian-Rui Liu
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Liang Fang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Duanduan Wan
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
| | - Meng Xiao
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Wuhan Institute of Quantum Technology, Wuhan 430206, China
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17
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Martello E, Singhal Y, Gadway B, Ozawa T, Price HM. Coexistence of stable and unstable population dynamics in a nonlinear non-Hermitian mechanical dimer. Phys Rev E 2023; 107:064211. [PMID: 37464675 DOI: 10.1103/physreve.107.064211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/31/2023] [Indexed: 07/20/2023]
Abstract
Non-Hermitian two-site dimers serve as minimal models in which to explore the interplay of gain and loss in dynamical systems. In this paper, we experimentally and theoretically investigate the dynamics of non-Hermitian dimer models with nonreciprocal hoppings between the two sites. We investigate two types of non-Hermitian couplings; one is when asymmetric hoppings are externally introduced, and the other is when the nonreciprocal hoppings depend on the population imbalance between the two sites, thus introducing the non-Hermiticity in a dynamical manner. We engineer the models in our synthetic mechanical setup comprised of two classical harmonic oscillators coupled by measurement-based feedback. For fixed nonreciprocal hoppings, we observe that, when the strength of these hoppings is increased, there is an expected transition from a PT-symmetric regime, where oscillations in the population are stable and bounded, to a PT-broken regime, where the oscillations are unstable and the population grows/decays exponentially. However, when the non-Hermiticity is dynamically introduced, we also find a third intermediate regime in which these two behaviors coexist, meaning that we can tune from stable to unstable population dynamics by simply changing the initial phase difference between the two sites. As we explain, this behavior can be understood by theoretically exploring the emergent fixed points of a related dimer model in which the nonreciprocal hoppings depend on the normalized population imbalance. Our study opens the way for the future exploration of non-Hermitian dynamics and exotic lattice models in synthetic mechanical networks.
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Affiliation(s)
- Enrico Martello
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Yaashnaa Singhal
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Bryce Gadway
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080, USA
| | - Tomoki Ozawa
- Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Hannah M Price
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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18
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Ju R, Xu G, Xu L, Qi M, Wang D, Cao PC, Xi R, Shou Y, Chen H, Qiu CW, Li Y. Convective Thermal Metamaterials: Exploring High-Efficiency, Directional, and Wave-Like Heat Transfer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2209123. [PMID: 36621882 DOI: 10.1002/adma.202209123] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/02/2022] [Indexed: 06/09/2023]
Abstract
Convective thermal metamaterials are artificial structures where convection dominates in the thermal process. Due to the field coupling between velocity and temperature, convection provides a new knob for controlling heat transfer beyond pure conduction, thus allowing active and robust thermal modulations. With the introduced convective effects, the original parabolic Fourier heat equation for pure conduction can be transformed to hyperbolic. Therefore, the hybrid diffusive system can be interpreted in a wave-like fashion, reviving many wave phenomena in dissipative diffusion. Here, recent advancements in convective thermal metamaterials are reviewed and the state-of-the-art discoveries are classified into the following four aspects, enhancing heat transfer, porous-media-based thermal effects, nonreciprocal heat transfer, and non-Hermitian phenomena. Finally, a prospect is cast on convective thermal metamaterials from two aspects. One is to utilize the convective parameter space to explore topological thermal effects. The other is to further broaden the convective parameter space with spatiotemporal modulation and multi-physical effects.
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Affiliation(s)
- Ran Ju
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Guoqiang Xu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Liujun Xu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
- Graduate School of China Academy of Engineering Physics, Beijing, 100193, China
| | - Minghong Qi
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Dong Wang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Pei-Chao Cao
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Rui Xi
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Yifan Shou
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Hongsheng Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore
| | - Ying Li
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou, 310027, China
- International Joint Innovation Center, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China
- Key Laboratory of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China
- Shaoxing Institute of Zhejiang University, Zhejiang University, Shaoxing, 312000, China
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19
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Akram J, Zheng C. Theoretical investigation of dynamics and concurrence of entangled [Formula: see text] and anti-[Formula: see text] symmetric polarized photons. Sci Rep 2023; 13:8542. [PMID: 37236997 PMCID: PMC10220064 DOI: 10.1038/s41598-023-34516-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023] Open
Abstract
Non-Hermitian systems with parity-time [Formula: see text] symmetry and anti-parity-time [Formula: see text] symmetry have exceptional points (EPs) resulting from eigenvector co-coalescence with exceptional properties. In the quantum and classical domains, higher-order EPs for [Formula: see text] symmetry and [Formula: see text]-symmetry systems have been proposed and realized. Both two-qubits [Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text] symmetric systems have seen an increase in recent years, especially in the dynamics of quantum entanglement. However, to our knowledge, neither theoretical nor experimental investigations have been conducted for the dynamics of two-qubits entanglement in the [Formula: see text]-[Formula: see text] symmetric system. We investigate the [Formula: see text]-[Formula: see text] dynamics for the first time. Moreover, we examine the impact of different initial Bell-state conditions on entanglement dynamics in [Formula: see text]-[Formula: see text], [Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text] symmetric systems. Additionally, we conduct a comparative study of entanglement dynamics in the [Formula: see text]-[Formula: see text] symmetrical system, [Formula: see text]-[Formula: see text] symmetrical system, and [Formula: see text]-[Formula: see text] symmetrical systems in order to learn more about non-Hermitian quantum systems and their environments. Entangled qubits evolve in a [Formula: see text]-[Formula: see text] symmetric unbroken regime, the entanglement oscillates with two different oscillation frequencies, and the entanglement is well preserved for a long period of time for the case when non-Hermitian parts of both qubits are taken quite away from the exceptional points.
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Affiliation(s)
- Javed Akram
- eleQtron GmbH, Martinshardt 19, 57074 Siegen, Germany
- Department of Physics, COMSATS University Islamabad, Islamabad, 45550 Pakistan
| | - Chao Zheng
- Department of Physics, College of Science, North China University of Technology, Beijing, 100144 China
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20
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Abstract
The topological properties of an object, associated with an integer called the topological invariant, are global features that cannot change continuously but only through abrupt variations, hence granting them intrinsic robustness. Engineered metamaterials (MMs) can be tailored to support highly nontrivial topological properties of their band structure, relative to their electronic, electromagnetic, acoustic and mechanical response, representing one of the major breakthroughs in physics over the past decade. Here, we review the foundations and the latest advances of topological photonic and phononic MMs, whose nontrivial wave interactions have become of great interest to a broad range of science disciplines, such as classical and quantum chemistry. We first introduce the basic concepts, including the notion of topological charge and geometric phase. We then discuss the topology of natural electronic materials, before reviewing their photonic/phononic topological MM analogues, including 2D topological MMs with and without time-reversal symmetry, Floquet topological insulators, 3D, higher-order, non-Hermitian and nonlinear topological MMs. We also discuss the topological aspects of scattering anomalies, chemical reactions and polaritons. This work aims at connecting the recent advances of topological concepts throughout a broad range of scientific areas and it highlights opportunities offered by topological MMs for the chemistry community and beyond.
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Affiliation(s)
- Xiang Ni
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
- School of Physics and Electronics, Central South University, Changsha, Hunan 410083, China
| | - Simon Yves
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
| | - Alex Krasnok
- Department of Electrical and Computer Engineering, Florida International University, Miami, Florida 33174, USA
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, United States
- Department of Electrical Engineering, City College, The City University of New York, 160 Convent Avenue, New York, New York 10031, United States
- Physics Program, The Graduate Center, The City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
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21
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Guo CX, Chen S, Ding K, Hu H. Exceptional Non-Abelian Topology in Multiband Non-Hermitian Systems. PHYSICAL REVIEW LETTERS 2023; 130:157201. [PMID: 37115861 DOI: 10.1103/physrevlett.130.157201] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 03/13/2023] [Indexed: 06/19/2023]
Abstract
Defective spectral degeneracy, known as exceptional point (EP), lies at the heart of various intriguing phenomena in optics, acoustics, and other nonconservative systems. Despite extensive studies in the past two decades, the collective behaviors (e.g., annihilation, coalescence, braiding, etc.) involving multiple exceptional points or lines and their interplay have been rarely understood. Here we put forward a universal non-Abelian conservation rule governing these collective behaviors in generic multiband non-Hermitian systems and uncover several counterintuitive phenomena. We demonstrate that two EPs with opposite charges (even the pairwise created) do not necessarily annihilate, depending on how they approach each other. Furthermore, we unveil that the conservation rule imposes strict constraints on the permissible exceptional-line configurations. It excludes structures like Hopf link yet permits novel staggered rings composed of noncommutative exceptional lines. These intriguing phenomena are illustrated by concrete models which could be readily implemented in platforms like coupled acoustic cavities, optical waveguides, and ring resonators. Our findings lay the cornerstone for a comprehensive understanding of the exceptional non-Abelian topology and shed light on the versatile manipulations and applications based on exceptional degeneracies in nonconservative systems.
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Affiliation(s)
- Cui-Xian Guo
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Shu Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Yangtze River Delta Physics Research Center, Liyang, Jiangsu 213300, China
| | - Kun Ding
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Haiping Hu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
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22
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Arkhipov II, Miranowicz A, Minganti F, Özdemir ŞK, Nori F. Dynamically crossing diabolic points while encircling exceptional curves: A programmable symmetric-asymmetric multimode switch. Nat Commun 2023; 14:2076. [PMID: 37045822 PMCID: PMC10097868 DOI: 10.1038/s41467-023-37275-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/10/2023] [Indexed: 04/14/2023] Open
Abstract
Nontrivial spectral properties of non-Hermitian systems can lead to intriguing effects with no counterparts in Hermitian systems. For instance, in a two-mode photonic system, by dynamically winding around an exceptional point (EP) a controlled asymmetric-symmetric mode switching can be realized. That is, the system can either end up in one of its eigenstates, regardless of the initial eigenmode, or it can switch between the two states on demand, by simply controlling the winding direction. However, for multimode systems with higher-order EPs or multiple low-order EPs, the situation can be more involved, and the ability to control asymmetric-symmetric mode switching can be impeded, due to the breakdown of adiabaticity. Here we demonstrate that this difficulty can be overcome by winding around exceptional curves by additionally crossing diabolic points. We consider a four-mode [Formula: see text]-symmetric bosonic system as a platform for experimental realization of such a multimode switch. Our work provides alternative routes for light manipulations in non-Hermitian photonic setups.
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Affiliation(s)
- Ievgen I Arkhipov
- Joint Laboratory of Optics of Palacký University and Institute of Physics of CAS, Faculty of Science, Palacký University, 17. listopadu 12, 771 46, Olomouc, Czech Republic.
| | - Adam Miranowicz
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University, 61-614, Poznań, Poland
| | - Fabrizio Minganti
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015, Lausanne, Switzerland
| | - Şahin K Özdemir
- Department of Engineering Science and Mechanics, and Materials Research Institute (MRI), The Pennsylvania State University, University Park, PA, 16802, USA
| | - Franco Nori
- Theoretical Quantum Physics Laboratory, Cluster for Pioneering Research, RIKEN, Wako-shi, Saitama, 351-0198, Japan.
- Quantum Information Physics Theory Research Team, Quantum Computing Center, RIKEN, Wakoshi, Saitama, 351-0198, Japan.
- Physics Department, The University of Michigan, Ann Arbor, MI, 48109-1040, USA.
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23
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Baek S, Park SH, Oh D, Lee K, Lee S, Lim H, Ha T, Park HS, Zhang S, Yang L, Min B, Kim TT. Non-Hermitian chiral degeneracy of gated graphene metasurfaces. LIGHT, SCIENCE & APPLICATIONS 2023; 12:87. [PMID: 37024464 PMCID: PMC10079968 DOI: 10.1038/s41377-023-01121-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 02/06/2023] [Accepted: 02/27/2023] [Indexed: 05/25/2023]
Abstract
Non-Hermitian degeneracies, also known as exceptional points (EPs), have been the focus of much attention due to their singular eigenvalue surface structure. Nevertheless, as pertaining to a non-Hermitian metasurface platform, the reduction of an eigenspace dimensionality at the EP has been investigated mostly in a passive repetitive manner. Here, we propose an electrical and spectral way of resolving chiral EPs and clarifying the consequences of chiral mode collapsing of a non-Hermitian gated graphene metasurface. More specifically, the measured non-Hermitian Jones matrix in parameter space enables the quantification of nonorthogonality of polarisation eigenstates and half-integer topological charges associated with a chiral EP. Interestingly, the output polarisation state can be made orthogonal to the coalesced polarisation eigenstate of the metasurface, revealing the missing dimension at the chiral EP. In addition, the maximal nonorthogonality at the chiral EP leads to a blocking of one of the cross-polarised transmission pathways and, consequently, the observation of enhanced asymmetric polarisation conversion. We anticipate that electrically controllable non-Hermitian metasurface platforms can serve as an interesting framework for the investigation of rich non-Hermitian polarisation dynamics around chiral EPs.
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Affiliation(s)
- Soojeong Baek
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Sang Hyun Park
- Department of Electrical and Computer Engineering, University of Minnesota, 200 Union street SE, Minneapolis, MN, 55455, USA
| | - Donghak Oh
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Kanghee Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
- Korea Research Institute of Standards and Science (KRISS), Gajeong-ro 267, Daejeon, 34113, Republic of Korea
| | - Sangha Lee
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea
| | - Hosub Lim
- Harvard Institute of Medicine, Harvard Medical School, Harvard University, Brigham and Women's Hospital, 25 Shattuck Street, Boston, MA, 02215, USA
| | - Taewoo Ha
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Seobu-ro 2066, Suwon, 16419, Republic of Korea
| | - Hyun Sung Park
- Samsung Advanced Institute of Technology, Samsung Electronics, Samsung-ro, Suwon, 16678, Republic of Korea
| | - Shuang Zhang
- Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region, China
| | - Lan Yang
- Department of Electrical and Systems Engineering, Washington University, 1 Brookings Drive, Saint Louis, MO, 63130, USA
| | - Bumki Min
- Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea.
- Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daehak-ro 291, Daejeon, 34141, Republic of Korea.
| | - Teun-Teun Kim
- Department of Physics, University of Ulsan, Daehak-ro, Ulsan, 44610, Republic of Korea.
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24
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Cayao J. Exceptional degeneracies in non-Hermitian Rashba semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:254002. [PMID: 37021876 DOI: 10.1088/1361-648x/acc7e9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 03/27/2023] [Indexed: 06/19/2023]
Abstract
Exceptional points (EPs) are spectral degeneracies of non-Hermitian (NH) systems where eigenvalues and eigenvectors coalesce, inducing unique topological phases that have no counterpart in the Hermitian realm. Here we consider an NH system by coupling a two-dimensional semiconductor with Rashba spin-orbit coupling (SOC) to a ferromagnet lead and show the emergence of highly tunable EPs along rings in momentum space. Interestingly, these exceptional degeneracies are the endpoints of lines formed by the eigenvalue coalescence at finite real energy, resembling the bulk Fermi arcs commonly defined at zero real energy. We then show that an in-plane Zeeman field provides a way to control these exceptional degeneracies although higher values of non-Hermiticity are required in contrast to the zero Zeeman field regime. Furthermore, we find that the spin projections also coalescence at the exceptional degeneracies and can acquire larger values than in the Hermitian regime. Finally, we demonstrate that the exceptional degeneracies induce large spectral weights, which can be used as a signature for their detection. Our results thus reveal the potential of systems with Rashba SOC for realizing NH bulk phenomena.
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Affiliation(s)
- Jorge Cayao
- Department of Physics and Astronomy, Uppsala University, Box 516, S-75120 Uppsala, Sweden
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25
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Bu JT, Zhang JQ, Ding GY, Li JC, Zhang JW, Wang B, Ding WQ, Yuan WF, Chen L, Özdemir ŞK, Zhou F, Jing H, Feng M. Enhancement of Quantum Heat Engine by Encircling a Liouvillian Exceptional Point. PHYSICAL REVIEW LETTERS 2023; 130:110402. [PMID: 37001093 DOI: 10.1103/physrevlett.130.110402] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/21/2022] [Accepted: 02/21/2023] [Indexed: 06/19/2023]
Abstract
Quantum heat engines are expected to outperform the classical counterparts due to quantum coherences involved. Here we experimentally execute a single-ion quantum heat engine and demonstrate, for the first time, the dynamics and the enhanced performance of the heat engine originating from the Liouvillian exceptional points (LEPs). In addition to the topological effects related to LEPs, we focus on thermodynamic effects, which can be understood by the Landau-Zener-Stückelberg process under decoherence. We witness a positive net work from the quantum heat engine if the heat engine cycle dynamically encircles a LEP. Further investigation reveals that a larger net work is done when the system is operated closer to the LEP. We attribute the enhanced performance of the quantum heat engine to the Landau-Zener-Stückelberg process, enabled by the eigenenergy landscape in the vicinity of the LEP, and the exceptional point-induced topological transition. Therefore, our results open new possibilities toward LEP-enabled control of quantum heat engines and of thermodynamic processes in open quantum systems.
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Affiliation(s)
- J-T Bu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-Q Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - G-Y Ding
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-C Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - J-W Zhang
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - B Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - W-Q Ding
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - W-F Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - L Chen
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - Ş K Özdemir
- Department of Engineering Science and Mechanics, and Materials Research Institute, Pennsylvania State University, University Park, State College, Pennsylvania 16802, USA
| | - F Zhou
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
| | - H Jing
- Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Department of Physics and Synergetic Innovation Center for Quantum Effects and Applications, Hunan Normal University, Changsha 410081, China
| | - M Feng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy of Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
- Research Center for Quantum Precision Measurement, Guangzhou Institute of Industry Technology, Guangzhou, 511458, China
- Department of Physics, Zhejiang Normal University, Jinhua 321004, China
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26
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Wurdack M, Yun T, Katzer M, Truscott AG, Knorr A, Selig M, Ostrovskaya EA, Estrecho E. Negative-mass exciton polaritons induced by dissipative light-matter coupling in an atomically thin semiconductor. Nat Commun 2023; 14:1026. [PMID: 36823076 PMCID: PMC9950362 DOI: 10.1038/s41467-023-36618-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 02/08/2023] [Indexed: 02/25/2023] Open
Abstract
Dispersion engineering is a powerful and versatile tool that can vary the speed of light signals and induce negative-mass effects in the dynamics of particles and quasiparticles. Here, we show that dissipative coupling between bound electron-hole pairs (excitons) and photons in an optical microcavity can lead to the formation of exciton polaritons with an inverted dispersion of the lower polariton branch and hence, a negative mass. We perform direct measurements of the anomalous dispersion in atomically thin (monolayer) WS2 crystals embedded in planar microcavities and demonstrate that the propagation direction of the negative-mass polaritons is opposite to their momentum. Our study introduces the concept of non-Hermitian dispersion engineering for exciton polaritons and opens a pathway for realising new phases of quantum matter in a solid state.
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Affiliation(s)
- M. Wurdack
- grid.1001.00000 0001 2180 7477ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601 Australia
| | - T. Yun
- grid.1001.00000 0001 2180 7477ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601 Australia ,grid.1002.30000 0004 1936 7857Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800 Australia ,grid.511002.7Songshan Lake Materials Laboratory, Dongguan, 523808 Guangdong China ,grid.9227.e0000000119573309Institute of Physics, Chinese Academy of Science, Beijing, 100190 China
| | - M. Katzer
- grid.6734.60000 0001 2292 8254Nichtlineare Optik und Quantenelektronik, Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - A. G. Truscott
- grid.1001.00000 0001 2180 7477Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601 Australia
| | - A. Knorr
- grid.6734.60000 0001 2292 8254Nichtlineare Optik und Quantenelektronik, Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - M. Selig
- grid.6734.60000 0001 2292 8254Nichtlineare Optik und Quantenelektronik, Institut für Theoretische Physik, Technische Universität Berlin, 10623 Berlin, Germany
| | - E. A. Ostrovskaya
- grid.1001.00000 0001 2180 7477ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601 Australia
| | - E. Estrecho
- grid.1001.00000 0001 2180 7477ARC Centre of Excellence in Future Low-Energy Electronics Technologies and Department of Quantum Science and Technology, Research School of Physics, The Australian National University, Canberra, ACT 2601 Australia
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27
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Feng Z, Sun X. Harnessing Dynamical Encircling of an Exceptional Point in Anti-PT-Symmetric Integrated Photonic Systems. PHYSICAL REVIEW LETTERS 2022; 129:273601. [PMID: 36638290 DOI: 10.1103/physrevlett.129.273601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 10/06/2022] [Indexed: 06/17/2023]
Abstract
Dynamically encircling an exceptional point in a non-Hermitian system can lead to chiral behaviors, but this process is difficult for on-chip PT-symmetric devices which require accurate control of gain and loss rates. Here, we experimentally demonstrated encircling an exceptional point with a fixed loss rate in a compact anti-PT-symmetric integrated photonic system, where chiral mode switching was achieved within a length that is an order of magnitude shorter than that of a PT-symmetric system. Based on the experimental demonstration, we proposed a topologically protected mode (de)multiplexer that is robust against fabrication errors with a wide operating wavelength range. With the advantages of simplified fabrication and characterization processes, the demonstrated system can be used for studying higher-order exceptional points and for exotic light manipulation.
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Affiliation(s)
- Ziyao Feng
- Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
| | - Xiankai Sun
- Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong
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28
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Soori A, Sivakumar M, Subrahmanyam V. Transmission across non-HermitianPT-symmetric quantum dots and ladders. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 35:055301. [PMID: 36395507 DOI: 10.1088/1361-648x/aca3ec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 11/17/2022] [Indexed: 06/16/2023]
Abstract
A non-Hermitian (NH) region connected to semi-infinite Hermitian lattices acts either as a source or as a sink and the probability current is not conserved in a scattering typically. Even aPT-symmetric region that contains both a source and a sink does not lead to current conservation plainly. We propose a model and study the scattering across a NHPT-symmetric two-level quantum dot (QD) connected to two semi-infinite one-dimensional lattices in a special way so that the probability current is conserved. Aharonov-Bohm type phases are included in the model, which arise from magnetic fluxes (ℏϕL/e, ℏϕR/e) through two loops in the system. We show that whenϕL=ϕR, the probability current is conserved. We find that the transmission across the QD can be perfect in thePT-unbroken phase (corresponding to real eigenenergies of the isolated QD) whereas the transmission is never perfect in thePT-broken phase (corresponding to purely imaginary eigenenergies of the QD). The two transmission peaks have the same width only for special values of the fluxes (being odd multiples ofπℏ/2e). In the broken phase, the transmission peak is surprisingly not at zero energy. We give an insight into this feature through a four-site toy model. We extend the model to aPT-symmetric ladder connected to two semi-infinite lattices. We show that the transmission is perfect in unbroken phase of the ladder due to Fabry-Pérot type interference, that can be controlled by tuning the chemical potential. In the broken phase of the ladder, the transmission is substantially suppressed.
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Affiliation(s)
- Abhiram Soori
- School of Physics, University of Hyderabad, C. R. Rao Road, Gachibowli, Hyderabad 500046, India
| | - M Sivakumar
- School of Physics, University of Hyderabad, C. R. Rao Road, Gachibowli, Hyderabad 500046, India
| | - V Subrahmanyam
- School of Physics, University of Hyderabad, C. R. Rao Road, Gachibowli, Hyderabad 500046, India
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29
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Tyc T, Cidlinský D. Spherical wedge billiard: From chaos to fractals and Talbot carpets. Phys Rev E 2022; 106:054202. [PMID: 36559389 DOI: 10.1103/physreve.106.054202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 10/12/2022] [Indexed: 06/17/2023]
Abstract
We introduce the spherical wedge billiard, a dynamical system consisting of a particle moving along a geodesic on a closed non-Euclidean surface of a spherical wedge. We derive the analytic form of the corresponding Poincaré map and find very complex dynamics, ranging from completely chaotic to very regular, exhibiting fractal features. Further, we show that upon changing the billiard parameter, the fixed points of the Poincaré map merge in complex ways, which has origin in the spherical aberration of the billiard mapping. We also analyze in detail the regular regime when phase space diagram is closely related to Talbot carpets.
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Affiliation(s)
- Tomáš Tyc
- Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic
| | - Darek Cidlinský
- Department of Theoretical Physics and Astrophysics, Faculty of Science, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic
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30
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Tang W, Ding K, Ma G. Experimental realization of non-Abelian permutations in a three-state non-Hermitian system. Natl Sci Rev 2022; 9:nwac010. [PMID: 36523566 PMCID: PMC9746695 DOI: 10.1093/nsr/nwac010] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 12/28/2021] [Accepted: 12/29/2021] [Indexed: 07/31/2023] Open
Abstract
Eigenstates of a non-Hermitian system exist on complex Riemannian manifolds, with multiple sheets connecting at branch cuts and exceptional points (EPs). These eigenstates can evolve across different sheets-a process that naturally corresponds to state permutation. Here, we report the first experimental realization of non-Abelian permutations in a three-state non-Hermitian system. Our approach relies on the stroboscopic encircling of two different exceptional arcs (EAs), which are smooth trajectories of order-2 EPs appearing from the coalescence of two adjacent states. The non-Abelian characteristics are confirmed by encircling the EAs in opposite sequences. A total of five non-trivial permutations are experimentally realized, which together comprise a non-Abelian group. Our approach provides a reliable way of investigating non-Abelian state permutations and the related exotic winding effects in non-Hermitian systems.
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Affiliation(s)
- Weiyuan Tang
- Department of Physics, Hong Kong Baptist University, Hong Kong, China
| | - Kun Ding
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai200438, China
| | - Guancong Ma
- Department of Physics, Hong Kong Baptist University, Hong Kong, China
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31
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Wang Y, Ren Y, Luo X, Li B, Chen Z, Liu Z, Liu F, Cai Y, Zhang Y, Liu J, Li F. Manipulating cavity photon dynamics by topologically curved space. LIGHT, SCIENCE & APPLICATIONS 2022; 11:308. [PMID: 36280661 PMCID: PMC9592597 DOI: 10.1038/s41377-022-01009-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/30/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
Asymmetric microcavities supporting Whispering-gallery modes (WGMs) are of great significance for on-chip optical information processing. We establish asymmetric microcavities on topologically curved surfaces, where the geodesic light trajectories completely reconstruct the cavity mode features. The curvature-mediated photon-lifetime engineering enables the enhancement of the quality factors of periodic island modes by up to 200 times. Strong and weak coupling between modes of very different origins occurs when the space curvature brings them into resonance, leading to fine tailoring of the cavity photon energy and lifetime and the observation of non-Hermitian exceptional point (EP). At large space curvatures, the role of the WGMs is replaced by high-Q periodic modes protected by the high stability of island-like light trajectory. Our work demonstrates interesting physical mechanisms at the crosspoint of optical chaotic dynamics, non-Hermitian physics, and geodesic optical devices, and would initiate the novel area of geodesic microcavity photonics.
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Grants
- National Natural Science Foundation of China (National Science Foundation of China)
- National Key R&D Program of China (2018YFA0306101 and 2021YFA1400800), National Natural Science Foundation of China (12074303, 11804267, 11904279, 62035017, 11874437, 12074442 and 91836303), Shaanxi Key Science and Technology Innovation Team Project (2021TD-56)
- National Key R&D Program of China (2018YFA0306101 and 2021YFA1400800), National Natural Science Foundation of China (12074303, 11804267, 11904279, 62035017, 11874437, 12074442 and 91836303), Shaanxi Key Science and Technology Innovation Team Project (2021TD-56).
- Key-Area Research and Development Program of Guangdong Province (2018B030329001), the Guangdong Special Support Program (2019JC05X397), the Local Innovative and Research Teams Project of the Guangdong Pearl River Talents Program (2017BT01X121) and the National Super-Computer Center in Guangzhou.
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Affiliation(s)
- Yongsheng Wang
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yuhao Ren
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou, China
| | - Xiaoxuan Luo
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Bo Li
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zaoyu Chen
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Zhenzhi Liu
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Fu Liu
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yin Cai
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Yanpeng Zhang
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou, China
| | - Feng Li
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique, School of Electronic Science and Engineering, Faculty of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
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32
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Łempicka-Mirek K, Król M, Sigurdsson H, Wincukiewicz A, Morawiak P, Mazur R, Muszyński M, Piecek W, Kula P, Stefaniuk T, Kamińska M, De Marco L, Lagoudakis PG, Ballarini D, Sanvitto D, Szczytko J, Piętka B. Electrically tunable Berry curvature and strong light-matter coupling in liquid crystal microcavities with 2D perovskite. SCIENCE ADVANCES 2022; 8:eabq7533. [PMID: 36197989 PMCID: PMC9534495 DOI: 10.1126/sciadv.abq7533] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/23/2022] [Indexed: 06/16/2023]
Abstract
The field of spinoptronics is underpinned by good control over photonic spin-orbit coupling in devices that have strong optical nonlinearities. Such devices might hold the key to a new era of optoelectronics where momentum and polarization degrees of freedom of light are interwoven and interfaced with electronics. However, manipulating photons through electrical means is a daunting task given their charge neutrality. In this work, we present electrically tunable microcavity exciton-polariton resonances in a Rashba-Dresselhaus spin-orbit coupling field. We show that different spin-orbit coupling fields and the reduced cavity symmetry lead to tunable formation of the Berry curvature, the hallmark of quantum geometrical effects. For this, we have implemented an architecture of a photonic structure with a two-dimensional perovskite layer incorporated into a microcavity filled with nematic liquid crystal. Our work interfaces spinoptronic devices with electronics by combining electrical control over both the strong light-matter coupling conditions and artificial gauge fields.
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Affiliation(s)
- Karolina Łempicka-Mirek
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Mateusz Król
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Helgi Sigurdsson
- Science Institute, University of Iceland, Dunhagi 3, IS-107 Reykjavik, Iceland
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
| | - Adam Wincukiewicz
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Przemysław Morawiak
- Institute of Applied Physics, Military University of Technology, Warsaw, Poland
| | - Rafał Mazur
- Institute of Applied Physics, Military University of Technology, Warsaw, Poland
| | - Marcin Muszyński
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Wiktor Piecek
- Institute of Applied Physics, Military University of Technology, Warsaw, Poland
| | - Przemysław Kula
- Institute of Chemistry, Military University of Technology, Warsaw, Poland
| | - Tomasz Stefaniuk
- Institute of Geophysics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warsaw, Poland
| | - Maria Kamińska
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Luisa De Marco
- CNR-Nanotec, Institute of Nanotechnology, Via Monteroni, 73100 Lecce, Italy
| | - Pavlos G. Lagoudakis
- Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, UK
- Hybrid Photonics Laboratory, Skolkovo Institute of Science and Technology, Territory of Innovation Center Skolkovo, 6 Bolshoy Boulevard 30, Building 1, 121205 Moscow, Russia
| | - Dario Ballarini
- CNR-Nanotec, Institute of Nanotechnology, Via Monteroni, 73100 Lecce, Italy
| | - Daniele Sanvitto
- CNR-Nanotec, Institute of Nanotechnology, Via Monteroni, 73100 Lecce, Italy
| | - Jacek Szczytko
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
| | - Barbara Piętka
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5, PL-02-093 Warsaw, Poland
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33
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Li A, Chen W, Wei H, Lu G, Alù A, Qiu CW, Chen L. Riemann-Encircling Exceptional Points for Efficient Asymmetric Polarization-Locked Devices. PHYSICAL REVIEW LETTERS 2022; 129:127401. [PMID: 36179197 DOI: 10.1103/physrevlett.129.127401] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 08/22/2022] [Indexed: 06/16/2023]
Abstract
Dynamically encircling exceptional points (EPs) have unveiled intriguing chiral dynamics in photonics. However, the traditional approach based on an open manifold of Hamiltonian parameter space fails to explore trajectories that pass through an infinite boundary. Here, by mapping the full parameter space onto a closed manifold of the Riemann sphere, we introduce a framework to describe encircling-EP loops. We demonstrate that an encircling trajectory crossing the north vertex can realize near-unity asymmetric transmission. An efficient gain-free, broadband asymmetric polarization-locked device is realized by mapping the encircling path onto L-shaped silicon waveguides.
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Affiliation(s)
- Aodong Li
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Weijin Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Heng Wei
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Guowei Lu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
| | - Andrea Alù
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, USA
- Physics Program, Graduate Center, City University of New York, New York, New York 10016, USA
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore
| | - Lin Chen
- Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
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34
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Król M, Septembre I, Oliwa P, Kędziora M, Łempicka-Mirek K, Muszyński M, Mazur R, Morawiak P, Piecek W, Kula P, Bardyszewski W, Lagoudakis PG, Solnyshkov DD, Malpuech G, Piętka B, Szczytko J. Annihilation of exceptional points from different Dirac valleys in a 2D photonic system. Nat Commun 2022; 13:5340. [PMID: 36096889 PMCID: PMC9468178 DOI: 10.1038/s41467-022-33001-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/26/2022] [Indexed: 12/03/2022] Open
Abstract
Topological physics relies on Hamiltonian’s eigenstate singularities carrying topological charges, such as Dirac points, and – in non-Hermitian systems – exceptional points (EPs), lines or surfaces. So far, the reported non-Hermitian topological transitions were related to the creation of a pair of EPs connected by a Fermi arc out of a single Dirac point by increasing non-Hermiticity. Such EPs can annihilate by reducing non-Hermiticity. Here, we demonstrate experimentally that an increase of non-Hermiticity can lead to the annihilation of EPs issued from different Dirac points (valleys). The studied platform is a liquid crystal microcavity with voltage-controlled birefringence and TE-TM photonic spin-orbit-coupling. Non-Hermiticity is provided by polarization-dependent losses. By increasing the non-Hermiticity degree, we control the position of the EPs. After the intervalley annihilation, the system becomes free of any band singularity. Our results open the field of non-Hermitian valley-physics and illustrate connections between Hermitian topology and non-Hermitian phase transitions. The authors study a liquid crystal microcavity with polarization-dependent absorption, a source of non-Hermiticity. The transition in the Hermitian topology of the spin-orbit coupling makes possible the annihilation of exceptional points.
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35
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Ferrier L, Bouteyre P, Pick A, Cueff S, Dang NHM, Diederichs C, Belarouci A, Benyattou T, Zhao JX, Su R, Xing J, Xiong Q, Nguyen HS. Unveiling the Enhancement of Spontaneous Emission at Exceptional Points. PHYSICAL REVIEW LETTERS 2022; 129:083602. [PMID: 36053693 DOI: 10.1103/physrevlett.129.083602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
Exceptional points (EPs), singularities of non-Hermitian physics where complex spectral resonances degenerate, are one of the most exotic features of nonequilibrium open systems with unique properties. For instance, the emission rate of quantum emitters placed near resonators with EPs is enhanced (compared to the free-space emission rate) by a factor that scales quadratically with the resonance quality factor. Here, we verify the theory of spontaneous emission at EPs by measuring photoluminescence from photonic-crystal slabs that are embedded with a high-quantum-yield active material. While our experimental results verify the theoretically predicted enhancement, they also highlight the practical limitations on the enhancement due to material loss. Our designed structures can be used in applications that require enhanced and controlled emission, such as quantum sensing and imaging.
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Affiliation(s)
- L Ferrier
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - P Bouteyre
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - A Pick
- Applied Physics Department, Hebrew University of Jerusalem, Israel
| | - S Cueff
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - N H M Dang
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - C Diederichs
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, F-75005 Paris, France
| | - A Belarouci
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - T Benyattou
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - J X Zhao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - R Su
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - J Xing
- College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Qihua Xiong
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
- Institut Universitaire de France (IUF), F-75231 Paris, France
| | - H S Nguyen
- Université Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
- Institut Universitaire de France (IUF), F-75231 Paris, France
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36
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Gwak S, Ryu J, Kim H, Yu HH, Kim CM, Yi CH. Far-Field Correlations Verifying Non-Hermitian Degeneracy of Optical Modes. PHYSICAL REVIEW LETTERS 2022; 129:074101. [PMID: 36018704 DOI: 10.1103/physrevlett.129.074101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
An experimental verification of an exceptional point (EP) in a stand-alone chaotic microcavity is a tough issue because as deformation parameters are fixed the traditional frequency analysis methods cannot be applied any more. Through numerical investigations with an asymmetric Reuleaux triangle microcavity (ARTM), we find that the eigenvalue difference of paired modes can approach near-zero regardless of nonorthogonality of the modes. In this case, for a definite verification of EPs in experiments, wave function coalescence should be confirmed. For this, we suggest the method of exploiting correlation of far-field patterns (FFPs), which is directly related to spatial mode patterns. In an ARTM, we demonstrate that the FFP correlation of paired modes can be used to confirm wave function coalescence when an eigenvalue difference approaches near zero.
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Affiliation(s)
- Sunjae Gwak
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Jinhyeok Ryu
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Hyundong Kim
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Hyeon-Hye Yu
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Chil-Min Kim
- Department of Physics and Chemistry, DGIST, Daegu 42988, Republic of Korea
| | - Chang-Hwan Yi
- Center for Theoretical Physics of Complex Systems, IBS, Daejeon 34126, Republic of Korea
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37
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Wang W, Wang X, Ma G. Non-Hermitian morphing of topological modes. Nature 2022; 608:50-55. [PMID: 35922504 DOI: 10.1038/s41586-022-04929-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 06/01/2022] [Indexed: 11/09/2022]
Abstract
Topological modes (TMs) are usually localized at defects or boundaries of a much larger topological lattice1,2. Recent studies of non-Hermitian band theories unveiled the non-Hermitian skin effect (NHSE), by which the bulk states collapse to the boundary as skin modes3-6. Here we explore the NHSE to reshape the wavefunctions of TMs by delocalizing them from the boundary. At a critical non-Hermitian parameter, the in-gap TMs even become completely extended in the entire bulk lattice, forming an 'extended mode outside of a continuum'. These extended modes are still protected by bulk-band topology, making them robust against local disorders. The morphing of TM wavefunction is experimentally realized in active mechanical lattices in both one-dimensional and two-dimensional topological lattices, as well as in a higher-order topological lattice. Furthermore, by the judicious engineering of the non-Hermiticity distribution, the TMs can deform into a diversity of shapes. Our findings not only broaden and deepen the current understanding of the TMs and the NHSE but also open new grounds for topological applications.
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Affiliation(s)
- Wei Wang
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Xulong Wang
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China
| | - Guancong Ma
- Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
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38
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Manipulating polariton condensates by Rashba-Dresselhaus coupling at room temperature. Nat Commun 2022; 13:3785. [PMID: 35778391 PMCID: PMC9249758 DOI: 10.1038/s41467-022-31529-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 06/17/2022] [Indexed: 11/17/2022] Open
Abstract
Spin-orbit coupling plays an important role in the spin Hall effect and topological insulators. Bose-Einstein condensates with spin-orbit coupling show remarkable quantum phase transition. In this work we control an exciton polariton condensate – a macroscopically coherent state of hybrid light and matter excitations – by virtue of the Rashba-Dresselhaus (RD) spin-orbit coupling. This is achieved in a liquid-crystal filled microcavity where CsPbBr3 perovskite microplates act as the gain material at room temperature. Specifically, we realize an artificial gauge field acting on the CsPbBr3 exciton polariton condensate, splitting the condensate fractions with opposite spins in both momentum and real space. Besides the ground states, higher-order discrete polariton modes can also be split by the RD effect. Our work paves the way to manipulate exciton polariton condensates with a synthetic gauge field based on the RD spin-orbit coupling at room temperature. Engineered spin-orbit coupling can induce novel quantum phases in a Bose-Einstein condensate, however such demonstrations have been limited to cold atom systems. Here the authors realize a exciton-polarion condensate with tunable spin-orbit coupling in a liquid crystal microcavity at room temperature.
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39
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Patil YSS, Höller J, Henry PA, Guria C, Zhang Y, Jiang L, Kralj N, Read N, Harris JGE. Measuring the knot of non-Hermitian degeneracies and non-commuting braids. Nature 2022; 607:271-275. [PMID: 35831605 DOI: 10.1038/s41586-022-04796-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/25/2022] [Indexed: 11/10/2022]
Abstract
Any system of coupled oscillators may be characterized by its spectrum of resonance frequencies (or eigenfrequencies), which can be tuned by varying the system's parameters. The relationship between control parameters and the eigenfrequency spectrum is central to a range of applications1-3. However, fundamental aspects of this relationship remain poorly understood. For example, if the controls are varied along a path that returns to its starting point (that is, around a 'loop'), the system's spectrum must return to itself. In systems that are Hermitian (that is, lossless and reciprocal), this process is trivial and each resonance frequency returns to its original value. However, in non-Hermitian systems, where the eigenfrequencies are complex, the spectrum may return to itself in a topologically non-trivial manner, a phenomenon known as spectral flow. The spectral flow is determined by how the control loop encircles degeneracies, and this relationship is well understood for [Formula: see text] (where [Formula: see text] is the number of oscillators in the system)4,5. Here we extend this description to arbitrary [Formula: see text]. We show that control loops generically produce braids of eigenfrequencies, and for [Formula: see text] these braids form a non-Abelian group that reflects the non-trivial geometry of the space of degeneracies. We demonstrate these features experimentally for [Formula: see text] using a cavity optomechanical system.
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Affiliation(s)
| | - Judith Höller
- Department of Physics, Yale University, New Haven, CT, USA.,Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, USA
| | - Parker A Henry
- Department of Applied Physics, Yale University, New Haven, CT, USA
| | - Chitres Guria
- Department of Physics, Yale University, New Haven, CT, USA
| | - Yiming Zhang
- Department of Physics, Yale University, New Haven, CT, USA
| | - Luyao Jiang
- Department of Physics, Yale University, New Haven, CT, USA
| | - Nenad Kralj
- Department of Physics, Yale University, New Haven, CT, USA.,Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Nicholas Read
- Department of Physics, Yale University, New Haven, CT, USA.,Department of Applied Physics, Yale University, New Haven, CT, USA.,Yale Quantum Institute, Yale University, New Haven, CT, USA
| | - Jack G E Harris
- Department of Physics, Yale University, New Haven, CT, USA. .,Department of Applied Physics, Yale University, New Haven, CT, USA. .,Yale Quantum Institute, Yale University, New Haven, CT, USA.
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40
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Peters KJH, Rodriguez SRK. Exceptional Precision of a Nonlinear Optical Sensor at a Square-Root Singularity. PHYSICAL REVIEW LETTERS 2022; 129:013901. [PMID: 35841548 DOI: 10.1103/physrevlett.129.013901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 03/27/2022] [Accepted: 06/05/2022] [Indexed: 06/15/2023]
Abstract
Exceptional points (EPs)-spectral singularities of non-Hermitian linear systems-have recently attracted interest for sensing. While initial proposals and experiments focused on enhanced sensitivities neglecting noise, subsequent studies revealed issues with EP sensors in noisy environments. Here we propose a single-mode Kerr-nonlinear resonator for exceptional sensing in noisy environments. Based on the resonator's dynamic hysteresis, we define a signal that displays a square-root singularity reminiscent of an EP. However, our sensor has crucial fundamental and practical advantages over EP sensors: the signal-to-noise ratio increases with the measurement speed, the square-root singularity is easily detected through intensity measurements, and both sensing precision and information content of the signal are enhanced around the singularity. Our sensor also overcomes the fundamental trade-off between precision and averaging time characterizing all linear sensors. All these unconventional features open up new opportunities for fast and precise sensing using hysteretic resonators.
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Affiliation(s)
- K J H Peters
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
| | - S R K Rodriguez
- Center for Nanophotonics, AMOLF, Science Park 104, 1098 XG Amsterdam, Netherlands
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41
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Knorr M, Manceau JM, Mornhinweg J, Nespolo J, Biasiol G, Tran NL, Malerba M, Goulain P, Lafosse X, Jeannin M, Stefinger M, Carusotto I, Lange C, Colombelli R, Huber R. Intersubband Polariton-Polariton Scattering in a Dispersive Microcavity. PHYSICAL REVIEW LETTERS 2022; 128:247401. [PMID: 35776456 DOI: 10.1103/physrevlett.128.247401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 03/10/2022] [Accepted: 04/15/2022] [Indexed: 06/15/2023]
Abstract
The ultrafast scattering dynamics of intersubband polaritons in dispersive cavities embedding GaAs/AlGaAs quantum wells are studied directly within their band structure using a noncollinear pump-probe geometry with phase-stable midinfrared pulses. Selective excitation of the lower polariton at a frequency of ∼25 THz and at a finite in-plane momentum k_{‖} leads to the emergence of a narrowband maximum in the probe reflectivity at k_{‖}=0. A quantum mechanical model identifies the underlying microscopic process as stimulated coherent polariton-polariton scattering. These results mark an important milestone toward quantum control and bosonic lasing in custom-tailored polaritonic systems in the mid and far infrared.
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Affiliation(s)
- M Knorr
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - J M Manceau
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - J Mornhinweg
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - J Nespolo
- INO-CNR BEC Center and Dipartimento di Fisica, Universita di Trento, I-38123 Povo, Italy
| | - G Biasiol
- Laboratorio TASC, CNR-IOM, Area Science Park, 34149 Basovizza, Trieste, Italy
| | - N L Tran
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - M Malerba
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - P Goulain
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - X Lafosse
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - M Jeannin
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - M Stefinger
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
| | - I Carusotto
- INO-CNR BEC Center and Dipartimento di Fisica, Universita di Trento, I-38123 Povo, Italy
| | - C Lange
- Department of Physics, TU Dortmund University, 44227 Dortmund, Germany
| | - R Colombelli
- Centre de Nanosciences et de Nanotechnologies (C2N), CNRS UMR 9001, Université Paris Saclay, 91120 Palaiseau, France
| | - R Huber
- Department of Physics, University of Regensburg, 93040 Regensburg, Germany
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42
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Linear response theory of open systems with exceptional points. Nat Commun 2022; 13:3281. [PMID: 35672311 PMCID: PMC9174331 DOI: 10.1038/s41467-022-30715-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 05/12/2022] [Indexed: 11/13/2022] Open
Abstract
Understanding the linear response of any system is the first step towards analyzing its linear and nonlinear dynamics, stability properties, as well as its behavior in the presence of noise. In non-Hermitian Hamiltonian systems, calculating the linear response is complicated due to the non-orthogonality of their eigenmodes, and the presence of exceptional points (EPs). Here, we derive a closed form series expansion of the resolvent associated with an arbitrary non-Hermitian system in terms of the ordinary and generalized eigenfunctions of the underlying Hamiltonian. This in turn reveals an interesting and previously overlooked feature of non-Hermitian systems, namely that their lineshape scaling is dictated by how the input (excitation) and output (collection) profiles are chosen. In particular, we demonstrate that a configuration with an EP of order M can exhibit a Lorentzian response or a super-Lorentzian response of order Ms with Ms = 2, 3, …, M, depending on the choice of input and output channels. The authors develop a closed-form expansion of the linear response associated with resonant non-Hermitian systems having exceptional points and demonstrate that the spectral response may involve different super Lorentzian lineshapes depending on the input/output channel configuration.
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43
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Observation of chiral state transfer without encircling an exceptional point. Nature 2022; 605:256-261. [PMID: 35546193 DOI: 10.1038/s41586-022-04542-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 02/14/2022] [Indexed: 11/08/2022]
Abstract
The adiabatic theorem, a corollary of the Schrödinger equation, manifests itself in a profoundly different way in non-Hermitian arrangements, resulting in counterintuitive state transfer schemes that have no counterpart in closed quantum systems. In particular, the dynamical encirclement of exceptional points (EPs) in parameter space has been shown to lead to a chiral phase accumulation, non-adiabatic jumps and topological mode conversion1-8. Recent theoretical studies, however, have shown that contrary to previously established demonstrations, this behaviour is not strictly a result of winding around a non-Hermitian degeneracy9. Instead, it seems to be mostly attributed to the non-trivial landscape of the Riemann surfaces, sometimes because of the presence of an EP in the vicinity9-11. Here, in an effort to bring this counterintuitive aspect of non-Hermitian systems to light and confirm this hypothesis, we provide a set of experiments to directly observe the field evolution and chiral state conversion in an EP-excluding cycle in a slowly varying non-Hermitian system. To do so, a versatile yet unique fibre-based photonic emulator is realized that utilizes the polarization degrees of freedom in a quasi-common-path single-ring arrangement. Our observations may open up new avenues for light manipulation and state conversion, as well as providing a foundation for understanding the intricacies of the adiabatic theorem in non-Hermitian systems.
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44
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Universal non-Hermitian skin effect in two and higher dimensions. Nat Commun 2022; 13:2496. [PMID: 35523795 PMCID: PMC9076925 DOI: 10.1038/s41467-022-30161-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 04/19/2022] [Indexed: 11/16/2022] Open
Abstract
Skin effect, experimentally discovered in one dimension, describes the physical phenomenon that on an open chain, an extensive number of eigenstates of a non-Hermitian Hamiltonian are localized at the end(s) of the chain. Here in two and higher dimensions, we establish a theorem that the skin effect exists, if and only if periodic-boundary spectrum of the Hamiltonian covers a finite area on the complex plane. This theorem establishes the universality of the effect, because the above condition is satisfied in almost every generic non-Hermitian Hamiltonian, and, unlike in one dimension, is compatible with all point-group symmetries. We propose two new types of skin effect in two and higher dimensions: the corner-skin effect where all eigenstates are localized at corners of the system, and the geometry-dependent-skin effect where skin modes disappear for systems of a particular shape, but appear on generic polygons. An immediate corollary of our theorem is that any non-Hermitian system having exceptional points (lines) in two (three) dimensions exhibits skin effect, making this phenomenon accessible to experiments in photonic crystals, Weyl semimetals, and Kondo insulators. The non-Hermitian skin effect has been discovered in a one dimensional open chain. Here, the authors establish the universality of this effect in two and higher dimensional non-Hermitian systems and propose two new types of skin effect.
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45
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Abbasi M, Chen W, Naghiloo M, Joglekar YN, Murch KW. Topological Quantum State Control through Exceptional-Point Proximity. PHYSICAL REVIEW LETTERS 2022; 128:160401. [PMID: 35522514 DOI: 10.1103/physrevlett.128.160401] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 01/12/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
We study the quantum evolution of a non-Hermitian qubit realized as a submanifold of a dissipative superconducting transmon circuit. Real-time tuning of the system parameters to encircle an exceptional point results in nonreciprocal quantum state transfer. We further observe chiral geometric phases accumulated under state transport, verifying the quantum coherent nature of the evolution in the complex energy landscape and distinguishing between coherent and incoherent effects associated with exceptional point encircling. Our work demonstrates an entirely new method for control over quantum state vectors, highlighting new facets of quantum bath engineering enabled through dynamical non-Hermitian control.
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Affiliation(s)
- Maryam Abbasi
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
| | - Weijian Chen
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Center for Quantum Sensors, Washington University, St. Louis, Missouri 63130, USA
| | - Mahdi Naghiloo
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Research Laboratory of Electronics, MIT, Cambridge, Massachusetts 02139, USA
| | - Yogesh N Joglekar
- Department of Physics, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, Indiana 46202, USA
| | - Kater W Murch
- Department of Physics, Washington University, St. Louis, Missouri 63130, USA
- Center for Quantum Sensors, Washington University, St. Louis, Missouri 63130, USA
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Tian C, Chen L, Zhang Y, Zhu L, Hu W, Pan Y, Wang Z, Zhang F, Zhang L, Dong H, Zhou W. Relaxation Oscillations of an Exciton-Polariton Condensate Driven by Parametric Scattering. NANO LETTERS 2022; 22:3026-3032. [PMID: 35343702 DOI: 10.1021/acs.nanolett.2c00235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We report the observation of coherent oscillations in the relaxation dynamics of an exciton-polariton condensate that were driven by parametric scattering processes. As a result of the interbranch scattering scheme and the nonlinear polariton-polariton interactions, such parametric scatterings exhibit a high scattering efficiency that leads to the fast depletion of the polariton condensate and the periodic shut-off of the bosonic stimulation processes, eventually causing relaxation oscillations. Employing polariton-reservoir interactions, the oscillation dynamics in the time domain can be projected onto the energy space. In theory, our simulations using the open-dissipative Gross-Pitaevskii equation are in excellent agreement with experimental observations. Surprisingly, the oscillation patterns, including many excitation pulses, are clearly visible in our time-integrated images, implying the high stability of the relaxation oscillations driven by polariton parametric scatterings.
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Affiliation(s)
- Chuan Tian
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Linqi Chen
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
| | - Yingjun Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
- Key Laboratory of Biomedical Engineering of Hainan Province, School of Biomedical Engineering, Hainan University, Haikou, Hainan 570100, China
| | - Liqing Zhu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Wenping Hu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Yichun Pan
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Zheng Wang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Fangxin Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Long Zhang
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang 310024, China
| | - Hongxing Dong
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang 310024, China
| | - Weihang Zhou
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
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Dóra B, Sticlet D, Moca CP. Correlations at PT-Symmetric Quantum Critical Point. PHYSICAL REVIEW LETTERS 2022; 128:146804. [PMID: 35476487 DOI: 10.1103/physrevlett.128.146804] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
We consider a PT-symmetric Fermi gas with an exceptional point, representing the critical point between PT-symmetric and symmetry broken phases. The low energy spectrum remains linear in momentum and is identical to that of a Hermitian Fermi gas. The fermionic Green's function decays in a power law fashion for large distances, as expected from gapless excitations, although the exponent is reduced from -1 due to the quantum Zeno effect. In spite of the gapless nature of the excitations, the ground state entanglement entropy saturates to a finite value, independent of the subsystem size due to the non-Hermitian correlation length intrinsic to the system. Attractive or repulsive interaction drives the system into the PT-symmetry broken regime or opens up a gap and protects PT symmetry, respectively. Our results challenge the concept of universality in non-Hermitian systems, where quantum criticality can be masked due to non-Hermiticity.
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Affiliation(s)
- Balázs Dóra
- Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary
- MTA-BME Lendület Topology and Correlation Research Group, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary
| | - Doru Sticlet
- National Institute for R&D of Isotopic and Molecular Technologies, 67-103 Donat, 400293 Cluj-Napoca, Romania
| | - Cătălin Paşcu Moca
- MTA-BME Quantum Dynamics and Correlations Research Group, Institute of Physics, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary
- Department of Physics, University of Oradea, 410087, Oradea, Romania
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Ergoktas MS, Soleymani S, Kakenov N, Wang K, Smith TB, Bakan G, Balci S, Principi A, Novoselov KS, Ozdemir SK, Kocabas C. Topological engineering of terahertz light using electrically tunable exceptional point singularities. Science 2022; 376:184-188. [PMID: 35389774 DOI: 10.1126/science.abn6528] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The topological structure associated with the branch point singularity around an exceptional point (EP) can provide tools for controlling the propagation of light. Through use of graphene-based devices, we demonstrate the emergence of EPs in an electrically controlled interaction between light and a collection of organic molecules in the terahertz regime at room temperature. We show that the intensity and phase of terahertz pulses can be controlled by a gate voltage, which drives the device across the EP. Our electrically tunable system allows reconstruction of the Riemann surface associated with the complex energy landscape and provides topological control of light by tuning the loss imbalance and frequency detuning of interacting modes. Our approach provides a platform for developing topological optoelectronics and studying the manifestations of EP physics in light-matter interactions.
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Affiliation(s)
- M Said Ergoktas
- Department of Materials, University of Manchester, Manchester, M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK
| | - Sina Soleymani
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802 USA
| | - Nurbek Kakenov
- Department of Physics, Bilkent University, Ankara, Turkey
| | - Kaiyuan Wang
- Department of Materials, University of Manchester, Manchester, M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK
| | - Thomas B Smith
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
| | - Gokhan Bakan
- Department of Materials, University of Manchester, Manchester, M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK
| | - Sinan Balci
- Department of Photonics, Izmir Institute of Technology, Izmir, Turkey
| | - Alessandro Principi
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
| | - Kostya S Novoselov
- Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK
| | - Sahin K Ozdemir
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802 USA.,Materials Research Institute, Pennsylvania State University, University Park, PA 16802, USA
| | - Coskun Kocabas
- Department of Materials, University of Manchester, Manchester, M13 9PL, UK.,National Graphene Institute, University of Manchester, Manchester, M13 9PL, UK.,Henry Royce Institute for Advanced Materials, University of Manchester, Manchester M13 9PL, UK
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Yu F, Zhang XL, Tian ZN, Chen QD, Sun HB. General Rules Governing the Dynamical Encircling of an Arbitrary Number of Exceptional Points. PHYSICAL REVIEW LETTERS 2021; 127:253901. [PMID: 35029432 DOI: 10.1103/physrevlett.127.253901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 11/15/2021] [Indexed: 06/14/2023]
Abstract
Dynamically encircling an exceptional point in non-Hermitian systems has drawn great attention recently, since a nonadiabatic transition process can occur and lead to intriguing phenomena and applications such as the asymmetric switching of modes. While all previous experiments have been restricted to two-state systems, the dynamics in multistate systems where more complex topology can be formed by exceptional points, is still unknown and associated experiments remain elusive. Here, we propose an on-chip photonic system in which an arbitrary number of exceptional points can be encircled dynamically. We reveal in experiment a robust state-switching rule for multistate systems, and extend it to an infinite-period system in which an exceptional line is encircled with outcomes being located at the Brillouin-zone boundary. The proposed versatile platform is expected to reveal more physics related to multiple exceptional points and exceptional lines, and give rise to applications in multistate non-Hermitian systems.
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Affiliation(s)
- Feng Yu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Xu-Lin Zhang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Zhen-Nan Tian
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Qi-Dai Chen
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Hong-Bo Sun
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
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50
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A new type of non-Hermitian phase transition in open systems far from thermal equilibrium. Sci Rep 2021; 11:24054. [PMID: 34912015 PMCID: PMC8674268 DOI: 10.1038/s41598-021-03389-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/29/2021] [Indexed: 01/15/2023] Open
Abstract
We demonstrate a new type of non-Hermitian phase transition in open systems far from thermal equilibrium, which can have place in the absence of an exceptional point. This transition takes place in coupled systems interacting with reservoirs at different temperatures. We show that the spectrum of energy flow through the system caused by the temperature gradient is determined by the [Formula: see text]-potential. Meanwhile, the frequency of the maximum in the spectrum plays the role of the order parameter. The phase transition manifests itself in the frequency splitting of the spectrum of energy flow at a critical point, the value of which is determined by the relaxation rates and the coupling strength. Near the critical point, fluctuations of the order parameter diverge according to a power law with the critical exponent that depends only on the ratio of reservoirs temperatures. The phase transition at the critical point has the non-equilibrium nature and leads to the change in the energy flow between the reservoirs. Our results pave the way to manipulate the heat energy transfer in the coupled out-of-equilibrium systems.
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