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Zhang H, Wang WW, Qiao C, Zhang L, Liang MC, Wu R, Wang XJ, Liu XJ, Zhang X. Topological spin-orbit-coupled fermions beyond rotating wave approximation. Sci Bull (Beijing) 2024; 69:747-755. [PMID: 38331706 DOI: 10.1016/j.scib.2024.01.018] [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: 11/03/2023] [Revised: 12/24/2023] [Accepted: 01/15/2024] [Indexed: 02/10/2024]
Abstract
The realization of spin-orbit-coupled ultracold gases has driven a wide range of research and is typically based on the rotating wave approximation (RWA). By neglecting the counter-rotating terms, RWA characterizes a single near-resonant spin-orbit (SO) coupling in a two-level system. Here, we propose and experimentally realize a new scheme for achieving a pair of two-dimensional (2D) SO couplings for ultracold fermions beyond RWA. This work not only realizes the first anomalous Floquet topological Fermi gas beyond RWA, but also significantly improves the lifetime of the 2D-SO-coupled Fermi gas. Based on pump-probe quench measurements, we observe a deterministic phase relation between two sets of SO couplings, which is characteristic of our beyond-RWA scheme and enables the two SO couplings to be simultaneously tuned to the optimum 2D configurations. We observe intriguing band topology by measuring two-ring band-inversion surfaces, quantitatively consistent with a Floquet topological Fermi gas in the regime of high Chern numbers. Our study can open an avenue to explore exotic SO physics and anomalous topological states based on long-lived SO-coupled ultracold fermions.
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Affiliation(s)
- Han Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Wen-Wei Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Chang Qiao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
| | - Long Zhang
- School of Physics and Institute for Quantum Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; Hefei National Laboratory, Hefei 230088, China
| | - Ming-Cheng Liang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Rui Wu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Xu-Jie Wang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Xiong-Jun Liu
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; Hefei National Laboratory, Hefei 230088, China; International Quantum Academy, Shenzhen 518048, China.
| | - Xibo Zhang
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China; Collaborative Innovation Center of Quantum Matter, Beijing 100871, China; Hefei National Laboratory, Hefei 230088, China; Beijing Academy of Quantum Information Sciences, Beijing 100193, China.
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2
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Lesne E, Saǧlam YG, Battilomo R, Mercaldo MT, van Thiel TC, Filippozzi U, Noce C, Cuoco M, Steele GA, Ortix C, Caviglia AD. Designing spin and orbital sources of Berry curvature at oxide interfaces. NATURE MATERIALS 2023; 22:576-582. [PMID: 36928382 PMCID: PMC10156604 DOI: 10.1038/s41563-023-01498-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 01/31/2023] [Indexed: 05/05/2023]
Abstract
Quantum materials can display physical phenomena rooted in the geometry of electronic wavefunctions. The corresponding geometric tensor is characterized by an emergent field known as the Berry curvature (BC). Large BCs typically arise when electronic states with different spin, orbital or sublattice quantum numbers hybridize at finite crystal momentum. In all the materials known to date, the BC is triggered by the hybridization of a single type of quantum number. Here we report the discovery of the first material system having both spin- and orbital-sourced BC: LaAlO3/SrTiO3 interfaces grown along the [111] direction. We independently detect these two sources and probe the BC associated to the spin quantum number through the measurements of an anomalous planar Hall effect. The observation of a nonlinear Hall effect with time-reversal symmetry signals large orbital-mediated BC dipoles. The coexistence of different forms of BC enables the combination of spintronic and optoelectronic functionalities in a single material.
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Affiliation(s)
- Edouard Lesne
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands.
- Max Planck Institute for Chemical Physics of Solids, Dresden, Germany.
| | - Yildiz G Saǧlam
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Raffaele Battilomo
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Utrecht, the Netherlands
| | | | - Thierry C van Thiel
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Ulderico Filippozzi
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Canio Noce
- Dipartimento di Fisica 'E. R. Caianiello', Universitá di Salerno, Fisciano, Italy
| | - Mario Cuoco
- CNR-SPIN c/o Universita' di Salerno, Fisciano, Italy
| | - Gary A Steele
- Kavli Institute of Nanoscience, Delft University of Technology, Delft, the Netherlands
| | - Carmine Ortix
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Utrecht, the Netherlands.
- Dipartimento di Fisica 'E. R. Caianiello', Universitá di Salerno, Fisciano, Italy.
| | - Andrea D Caviglia
- Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland.
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3
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Sedov DD, Kozin VK, Iorsh IV. Chiral Waveguide Optomechanics: First Order Quantum Phase Transitions with Z_{3} Symmetry Breaking. PHYSICAL REVIEW LETTERS 2020; 125:263606. [PMID: 33449725 DOI: 10.1103/physrevlett.125.263606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/09/2020] [Indexed: 06/12/2023]
Abstract
We present a direct mapping between the quantum optomechanical problem of the atoms harmonically trapped in the vicinity of a chiral waveguide and a generalized quantum Rabi model, and we discuss the analogy between the self-organization of atomic chains in photonic structures and Dicke-like quantum phase transitions in the ultrastrong coupling regime. We extend the class of the superradiant phase transitions for the systems possessing Z_{3} rather than parity Z_{2} symmetry and demonstrate the emergence of the multicomponent Schrödinger-cat ground states in these systems.
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Affiliation(s)
- D D Sedov
- Department of Physics and Engineering, ITMO University, Saint Petersburg 197101, Russia
| | - V K Kozin
- Department of Physics and Engineering, ITMO University, Saint Petersburg 197101, Russia
- Science Institute, University of Iceland, Dunhagi-3, IS-107 Reykjavik, Iceland
| | - I V Iorsh
- Department of Physics and Engineering, ITMO University, Saint Petersburg 197101, Russia
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Zhang S, Go G, Lee KJ, Kim SK. SU(3) Topology of Magnon-Phonon Hybridization in 2D Antiferromagnets. PHYSICAL REVIEW LETTERS 2020; 124:147204. [PMID: 32338956 DOI: 10.1103/physrevlett.124.147204] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
Magnon-phonon hybrid excitations are studied theoretically in a two-dimensional antiferromagnet with an easy axis normal to the plane. We show that two magnon bands and one phonon band are intertwined by the magnetoelastic coupling through a nontrivial SU(3) topology, which can be intuitively perceived by identifying a skyrmion structure in the momentum space. Our results are insensitive to lattice details and generally applicable to two-dimensional antiferromagnets. We show this by developing a continuum theory as the long-wavelength approximation to the tight-binding model. The theoretical results can be probed by measuring the thermal Hall conductance as a function of the temperature and the magnetic field. We envision that the magnetoelastic coupling in antiferromagnets can be a promising venue in search of various topological excitations, which cannot be found in magnetic or elastic models alone.
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Affiliation(s)
- Shu Zhang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Gyungchoon Go
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Se Kwon Kim
- Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA
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5
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Downing CA, Sturges TJ, Weick G, Stobińska M, Martín-Moreno L. Topological Phases of Polaritons in a Cavity Waveguide. PHYSICAL REVIEW LETTERS 2019; 123:217401. [PMID: 31809145 DOI: 10.1103/physrevlett.123.217401] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Indexed: 06/10/2023]
Abstract
We study the unconventional topological phases of polaritons inside a cavity waveguide, demonstrating how strong light-matter coupling leads to a breakdown of the bulk-edge correspondence. We observe an ostensibly topologically nontrivial phase, which unexpectedly does not exhibit edge states. Our findings are in direct contrast to topological tight-binding models with electrons, such as the celebrated Su-Schrieffer-Heeger (SSH) model. We present a theory of collective polaritonic excitations in a dimerized chain of oscillating dipoles embedded inside a photonic cavity. The added degree of freedom from the cavity photons upgrades the system from a typical SSH SU(2) model into a largely unexplored SU(3) model. Tuning the light-matter coupling strength by changing the cavity size reveals three critical points in parameter space: when the polariton band gap closes, when the Zak phase changes from being trivial to nontrivial, and when the edge state is lost. These three critical points do not coincide, and thus the Zak phase is no longer an indicator of the presence of edge states. Our discoveries demonstrate some remarkable properties of topological matter when strongly coupled to light, and could be important for the growing field of topological nanophotonics.
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Affiliation(s)
- C A Downing
- Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza E-50009, Spain
| | - T J Sturges
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - G Weick
- Université de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504, F-67000 Strasbourg, France
| | - M Stobińska
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warsaw, Poland
| | - L Martín-Moreno
- Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, Zaragoza E-50009, Spain
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6
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Han W, Zhang XF, Wang DS, Jiang HF, Zhang W, Zhang SG. Chiral Supersolid in Spin-Orbit-Coupled Bose Gases with Soft-Core Long-Range Interactions. PHYSICAL REVIEW LETTERS 2018; 121:030404. [PMID: 30085824 DOI: 10.1103/physrevlett.121.030404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Indexed: 06/08/2023]
Abstract
Chirality represents a kind of symmetry breaking characterized by the noncoincidence of an object with its mirror image and has been attracting intense attention in a broad range of scientific areas. The recent realization of spin-orbit coupling in ultracold atomic gases provides a new perspective to study quantum states with chirality. In this Letter, we demonstrate that the combined effects of spin-orbit coupling and interatomic soft-core long-range interaction can induce an exotic supersolid phase in which the chiral symmetry is broken with spontaneous emergence of circulating particle current. This implies that a finite angular momentum can be generated with neither rotation nor effective magnetic field. The direction of the angular momentum can be altered by adjusting the strength of spin-orbit coupling or interatomic interaction. The predicted chiral supersolid phase can be experimentally observed in Rydberg-dressed Bose-Einstein condensates with spin-orbit coupling.
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Affiliation(s)
- Wei Han
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China
- School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiao-Fei Zhang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China
- School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Deng-Shan Wang
- School of Science, Beijing Information Science and Technology University, Beijing 100192, China
| | - Hai-Feng Jiang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China
- School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Zhang
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Shou-Gang Zhang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi'an 710600, China
- School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China
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Goldman N, Juzeliūnas G, Öhberg P, Spielman IB. Light-induced gauge fields for ultracold atoms. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:126401. [PMID: 25422950 DOI: 10.1088/0034-4885/77/12/126401] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Gauge fields are central in our modern understanding of physics at all scales. At the highest energy scales known, the microscopic universe is governed by particles interacting with each other through the exchange of gauge bosons. At the largest length scales, our Universe is ruled by gravity, whose gauge structure suggests the existence of a particle-the graviton-that mediates the gravitational force. At the mesoscopic scale, solid-state systems are subjected to gauge fields of different nature: materials can be immersed in external electromagnetic fields, but they can also feature emerging gauge fields in their low-energy description. In this review, we focus on another kind of gauge field: those engineered in systems of ultracold neutral atoms. In these setups, atoms are suitably coupled to laser fields that generate effective gauge potentials in their description. Neutral atoms 'feeling' laser-induced gauge potentials can potentially mimic the behavior of an electron gas subjected to a magnetic field, but also, the interaction of elementary particles with non-Abelian gauge fields. Here, we review different realized and proposed techniques for creating gauge potentials-both Abelian and non-Abelian-in atomic systems and discuss their implication in the context of quantum simulation. While most of these setups concern the realization of background and classical gauge potentials, we conclude with more exotic proposals where these synthetic fields might be made dynamical, in view of simulating interacting gauge theories with cold atoms.
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Affiliation(s)
- N Goldman
- College de France, 11 place Marcelin Berthelot & Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, 75005 Paris, France
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