1
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Liles SD, Halverson DJ, Wang Z, Shamim A, Eggli RS, Jin IK, Hillier J, Kumar K, Vorreiter I, Rendell MJ, Huang JY, Escott CC, Hudson FE, Lim WH, Culcer D, Dzurak AS, Hamilton AR. A singlet-triplet hole-spin qubit in MOS silicon. Nat Commun 2024; 15:7690. [PMID: 39227367 PMCID: PMC11372177 DOI: 10.1038/s41467-024-51902-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 08/19/2024] [Indexed: 09/05/2024] Open
Abstract
Holes in silicon quantum dots are promising for spin qubit applications due to the strong intrinsic spin-orbit coupling. The spin-orbit coupling produces complex hole-spin dynamics, providing opportunities to further optimise spin qubits. Here, we demonstrate a singlet-triplet qubit using hole states in a planar metal-oxide-semiconductor double quantum dot. We demonstrate rapid qubit control with singlet-triplet oscillations up to 400 MHz. The qubit exhibits promising coherence, with a maximum dephasing time of 600 ns, which is enhanced to 1.3 μs using refocusing techniques. We investigate the magnetic field anisotropy of the eigenstates, and determine a magnetic field orientation to improve the qubit initialisation fidelity. These results present a step forward for spin qubit technology, by implementing a high quality singlet-triplet hole-spin qubit in planar architecture suitable for scaling up to 2D arrays of coupled qubits.
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Affiliation(s)
- S D Liles
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia.
| | - D J Halverson
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Z Wang
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - A Shamim
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - R S Eggli
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056, Basel, Switzerland
| | - I K Jin
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
- Center for Emergent Matter Science, RIKEN, 2-1, Hirosawa, Wako-shi, 351-0198, Saitama, Japan
| | - J Hillier
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - K Kumar
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - I Vorreiter
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - M J Rendell
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - J Y Huang
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, Australia
| | - C C Escott
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, Australia
| | - F E Hudson
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, Australia
| | - W H Lim
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, Australia
| | - D Culcer
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
| | - A S Dzurak
- School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, NSW, 2052, Australia
- Diraq, Sydney, NSW, Australia
| | - A R Hamilton
- School of Physics, University of New South Wales, Sydney, NSW, 2052, Australia
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2
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Hecker K, Banszerus L, Schäpers A, Möller S, Peters A, Icking E, Watanabe K, Taniguchi T, Volk C, Stampfer C. Coherent charge oscillations in a bilayer graphene double quantum dot. Nat Commun 2023; 14:7911. [PMID: 38036517 PMCID: PMC10689829 DOI: 10.1038/s41467-023-43541-3] [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: 03/14/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023] Open
Abstract
The coherent dynamics of a quantum mechanical two-level system passing through an anti-crossing of two energy levels can give rise to Landau-Zener-Stückelberg-Majorana (LZSM) interference. LZSM interference spectroscopy has proven to be a fruitful tool to investigate charge noise and charge decoherence in semiconductor quantum dots (QDs). Recently, bilayer graphene has developed as a promising platform to host highly tunable QDs potentially useful for hosting spin and valley qubits. So far, in this system no coherent oscillations have been observed and little is known about charge noise in this material. Here, we report coherent charge oscillations and [Formula: see text] charge decoherence times in a bilayer graphene double QD. The charge decoherence times are measured independently using LZSM interference and photon assisted tunneling. Both techniques yield [Formula: see text] average values in the range of 400-500 ps. The observation of charge coherence allows to study the origin and spectral distribution of charge noise in future experiments.
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Affiliation(s)
- K Hecker
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany.
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany.
| | - L Banszerus
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Schäpers
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - S Möller
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - A Peters
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
| | - E Icking
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - K Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - T Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
| | - C Volk
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - C Stampfer
- JARA-FIT and 2nd Institute of Physics, RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
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3
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Chowdhury A, Le AT, Weig EM, Ribeiro H. Iterative Adaptive Spectroscopy of Short Signals. PHYSICAL REVIEW LETTERS 2023; 131:050802. [PMID: 37595240 DOI: 10.1103/physrevlett.131.050802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 02/01/2023] [Accepted: 06/12/2023] [Indexed: 08/20/2023]
Abstract
We develop an iterative, adaptive frequency sensing protocol based on Ramsey interferometry of a two-level system. Our scheme allows one to estimate unknown frequencies with a high precision from short, finite signals consisting of only a small number of Ramsey fringes. It avoids several issues related to processing of decaying signals and reduces the experimental overhead related to sampling. High precision is achieved by enhancing the Ramsey sequence to prepare with high fidelity both the sensing and readout state and by using an iterative procedure built to mitigate systematic errors when estimating frequencies from Fourier transforms. A comparison with state-of-the-art dynamical decoupling techniques reveals a significant speedup of the frequency estimation without loss of precision.
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Affiliation(s)
- Avishek Chowdhury
- School of Computation, Information and Technology, Technical University of Munich, 85748 Garching, Germany
| | - Anh Tuan Le
- School of Computation, Information and Technology, Technical University of Munich, 85748 Garching, Germany
| | - Eva M Weig
- School of Computation, Information and Technology, Technical University of Munich, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, 80799 Munich, Germany
- TUM Center for Quantum Engineering (ZQE), Am Coulombwall 3A, 85748 Garching, Germany
| | - Hugo Ribeiro
- Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA
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4
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Jang W, Kim J, Park J, Kim G, Cho MK, Jang H, Sim S, Kang B, Jung H, Umansky V, Kim D. Wigner-molecularization-enabled dynamic nuclear polarization. Nat Commun 2023; 14:2948. [PMID: 37221217 DOI: 10.1038/s41467-023-38649-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 05/10/2023] [Indexed: 05/25/2023] Open
Abstract
Multielectron semiconductor quantum dots (QDs) provide a novel platform to study the Coulomb interaction-driven, spatially localized electron states of Wigner molecules (WMs). Although Wigner-molecularization has been confirmed by real-space imaging and coherent spectroscopy, the open system dynamics of the strongly correlated states with the environment are not yet well understood. Here, we demonstrate efficient control of spin transfer between an artificial three-electron WM and the nuclear environment in a GaAs double QD. A Landau-Zener sweep-based polarization sequence and low-lying anticrossings of spin multiplet states enabled by Wigner-molecularization are utilized. Combined with coherent control of spin states, we achieve control of magnitude, polarity, and site dependence of the nuclear field. We demonstrate that the same level of control cannot be achieved in the non-interacting regime. Thus, we confirm the spin structure of a WM, paving the way for active control of correlated electron states for application in mesoscopic environment engineering.
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Affiliation(s)
- Wonjin Jang
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Jehyun Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Jaemin Park
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Gyeonghun Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Min-Kyun Cho
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Hyeongyu Jang
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Sangwoo Sim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Byoungwoo Kang
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea
| | - Hwanchul Jung
- Department of Physics, Pusan National University, Busan, 46241, Korea
| | - Vladimir Umansky
- Braun Center for Submicron Research, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Dohun Kim
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul, 08826, Korea.
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5
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Wang S, Qin C, Zhao L, Ye H, Longhi S, Lu P, Wang B. Photonic Floquet Landau-Zener tunneling and temporal beam splitters. SCIENCE ADVANCES 2023; 9:eadh0415. [PMID: 37134159 PMCID: PMC10156109 DOI: 10.1126/sciadv.adh0415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Landau-Zener tunneling (LZT), i.e., the nonadiabatic transition under strong parameter driving in multilevel systems, is ubiquitous in physics, providing a powerful tool for coherent wave control both in quantum and classical systems. While previous works mainly focus on LZT between two energy bands in time-invariant crystals, here, we construct synthetic time-periodic temporal lattices from two coupled fiber loops and demonstrate dc- and ac-driven LZTs between periodic Floquet bands. We show that dc- and ac-driven LZTs display distinctive tunneling and interference characteristics, which can be harnessed to realize fully reconfigurable LZT beam splitter arrangements. As a potential application to signal processing, we realize a 4-bit temporal beam encoder for classical light pulses using a reconfigurable LZT beam splitter network. Our work introduces and experimentally demonstrates a new class of reconfigurable linear optics circuits harnessing Floquet LZT, which may find versatile applications in temporal beam control, signal processing, quantum simulations, and information processing.
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Affiliation(s)
- Shulin Wang
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Chengzhi Qin
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Lange Zhao
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Han Ye
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Stefano Longhi
- Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
- IFISC (UIB-CSIC), Instituto de Fisica Interdisciplinar y Sistemas Complejos, E-07122 Palma de Mallorca, Spain
| | - Peixiang Lu
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
- Hubei Key Laboratory of Optical Information and Pattern Recognition, Wuhan Institute of Technology, Wuhan 430205, China
| | - Bing Wang
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
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6
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Circuit quantum electrodynamics with dressed states of a superconducting artificial atom. Sci Rep 2022; 12:22308. [PMID: 36566268 PMCID: PMC9789979 DOI: 10.1038/s41598-022-26828-1] [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: 10/04/2022] [Accepted: 12/20/2022] [Indexed: 12/25/2022] Open
Abstract
A dynamical control of the coupling strengths between dressed states and probe photon states is demonstrated with a transmon-like artificial atom coupled to two closely spaced resonant modes. When the atom is driven with one mode, the atom state and driving photon states form the so-called dressed states. Dressed states with sideband index up to 3 were prepared and probed via the strong coupling to the other resonant mode. Spectroscopy reveals that the coupling strengths are "dressed" and can be modulated by the power and sideband index of the driving. The transmission of the probe tone is modulated by the driving microwave amplitude with a Bessel behavior, displaying multi-photon process associated with the inter-atomic level transitions.
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7
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Chang CC, Chen YH, Chen GY, Lin L. Manipulating quantum interference of dressed photon fields. OPTICS EXPRESS 2022; 30:18156-18167. [PMID: 36221622 DOI: 10.1364/oe.455247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/01/2022] [Indexed: 06/16/2023]
Abstract
Through quantum electrodynamics (QED) we investigate the interactions between a three-level atom and two photon fields under perturbation limit. The dispersion relation and (relative) transmission of the probe photons are obtained by calculating the corresponding Feynman diagrams. The quantum interference in this three-level system such as Fano resonance and electromagnetically induced transparency (EIT) can be tuned by varying the intensities of the control and probe beams. Moreover, by considering that the control beam with periodic modulation, that is, the so-called Landau-Zener-Stückelberg (LZS) type source, the accumulated phase after Landau-Zener transitions is found to show the alternating Fano (EIT) lineshapes in the transmission of the probe photons. We further find that the transmissions can become almost stationary in addition to a wide EIT window in time even though the control beam is a LZS-type oscillating source.
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8
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Jirovec D, Mutter PM, Hofmann A, Crippa A, Rychetsky M, Craig DL, Kukucka J, Martins F, Ballabio A, Ares N, Chrastina D, Isella G, Burkard G, Katsaros G. Dynamics of Hole Singlet-Triplet Qubits with Large g-Factor Differences. PHYSICAL REVIEW LETTERS 2022; 128:126803. [PMID: 35394319 DOI: 10.1103/physrevlett.128.126803] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 01/24/2022] [Accepted: 02/24/2022] [Indexed: 06/14/2023]
Abstract
The spin-orbit interaction permits to control the state of a spin qubit via electric fields. For holes it is particularly strong, allowing for fast all electrical qubit manipulation, and yet an in-depth understanding of this interaction in hole systems is missing. Here we investigate, experimentally and theoretically, the effect of the cubic Rashba spin-orbit interaction on the mixing of the spin states by studying singlet-triplet oscillations in a planar Ge hole double quantum dot. Landau-Zener sweeps at different magnetic field directions allow us to disentangle the effects of the spin-orbit induced spin-flip term from those caused by strongly site-dependent and anisotropic quantum dot g tensors. Our work, therefore, provides new insights into the hole spin-orbit interaction, necessary for optimizing future qubit experiments.
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Affiliation(s)
- Daniel Jirovec
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Philipp M Mutter
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Andrea Hofmann
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Alessandro Crippa
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa, Italy
| | - Marek Rychetsky
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - David L Craig
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Josip Kukucka
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Frederico Martins
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
- Hitachi Cambridge Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Andrea Ballabio
- L-NESS, Physics Department, Politecnico di Milano, via Anzani 42, 22100, Como, Italy
| | - Natalia Ares
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
| | - Daniel Chrastina
- L-NESS, Physics Department, Politecnico di Milano, via Anzani 42, 22100, Como, Italy
| | - Giovanni Isella
- L-NESS, Physics Department, Politecnico di Milano, via Anzani 42, 22100, Como, Italy
| | - Guido Burkard
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Georgios Katsaros
- Institute of Science and Technology Austria (ISTA), Am Campus 1, 3400 Klosterneuburg, Austria
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9
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Jirovec D, Hofmann A, Ballabio A, Mutter PM, Tavani G, Botifoll M, Crippa A, Kukucka J, Sagi O, Martins F, Saez-Mollejo J, Prieto I, Borovkov M, Arbiol J, Chrastina D, Isella G, Katsaros G. A singlet-triplet hole spin qubit in planar Ge. NATURE MATERIALS 2021; 20:1106-1112. [PMID: 34083775 DOI: 10.1038/s41563-021-01022-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Spin qubits are considered to be among the most promising candidates for building a quantum processor. Group IV hole spin qubits are particularly interesting owing to their ease of operation and compatibility with Si technology. In addition, Ge offers the option for monolithic superconductor-semiconductor integration. Here, we demonstrate a hole spin qubit operating at fields below 10 mT, the critical field of Al, by exploiting the large out-of-plane hole g-factors in planar Ge and by encoding the qubit into the singlet-triplet states of a double quantum dot. We observe electrically controlled g-factor difference-driven and exchange-driven rotations with tunable frequencies exceeding 100 MHz and dephasing times of 1 μs, which we extend beyond 150 μs using echo techniques. These results demonstrate that Ge hole singlet-triplet qubits are competing with state-of-the-art GaAs and Si singlet-triplet qubits. In addition, their rotation frequencies and coherence are comparable with those of Ge single spin qubits, but singlet-triplet qubits can be operated at much lower fields, emphasizing their potential for on-chip integration with superconducting technologies.
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Affiliation(s)
- Daniel Jirovec
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
| | - Andrea Hofmann
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Andrea Ballabio
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Philipp M Mutter
- Department of Physics, University of Konstanz, Konstanz, Germany
| | - Giulio Tavani
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Marc Botifoll
- Catalan Institute of Nanoscience and Nanotechnology, Spanish National Research Council, Barcelona Institute of Science and Technology, Autonomous University of Barcelona, Barcelona, Spain
| | - Alessandro Crippa
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Josip Kukucka
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Oliver Sagi
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Frederico Martins
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Ivan Prieto
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Maksim Borovkov
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jordi Arbiol
- Catalan Institute of Nanoscience and Nanotechnology, Spanish National Research Council, Barcelona Institute of Science and Technology, Autonomous University of Barcelona, Barcelona, Spain
- Catalan Institution for Research and Advanced Studies, Barcelona, Spain
| | - Daniel Chrastina
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Giovanni Isella
- Laboratory for Epitaxial Nanostructures on Silicon and Spintronics, Physics Department, Politecnico di Milano, Como, Italy
| | - Georgios Katsaros
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
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10
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Gao L, Sun K, Zheng H, Zhao Y. A Deep‐Learning Approach to the Dynamics of Landau–Zenner Transitions. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202100083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Linliang Gao
- School of Science Hangzhou Dianzi University Hangzhou 310018 China
- Division of Materials Science Nanyang Technological University Singapore 639798 Singapore
| | - Kewei Sun
- School of Science Hangzhou Dianzi University Hangzhou 310018 China
| | - Huiru Zheng
- School of Computing Ulster University at Jordanstown Newtownabbey, Co. Antrim BT37 0QB UK
| | - Yang Zhao
- Division of Materials Science Nanyang Technological University Singapore 639798 Singapore
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11
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Zheng F, Shen Y, Sun K, Zhao Y. Photon-assisted Landau-Zener transitions in a periodically driven Rabi dimer coupled to a dissipative mode. J Chem Phys 2021; 154:044102. [PMID: 33514079 DOI: 10.1063/5.0033545] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate multiple photon-assisted Landau-Zener (LZ) transitions in a hybrid circuit quantum electrodynamics device in which each of two interacting transmission-line resonators is coupled to a qubit, and the qubits are driven by periodic driving fields and also coupled to a common phonon mode. The quantum state of the entire composite system is modeled using the multi-D2Ansatz in combination with the time-dependent Dirac-Frenkel variational principle. Applying a sinusoidal driving field to one of the qubits, this device is an ideal platform to study the photon-assisted LZ transitions by comparing the dynamics of the two qubits. A series of interfering photon-assisted LZ transitions takes place if the photon frequency is much smaller than the driving amplitude. Once the two energy scales are comparable, independent LZ transitions arise and a transition pathway is revealed using an energy diagram. It is found that both adiabatic and nonadiabatic transitions are involved in the dynamics. Used to model environmental effects on the LZ transitions, the common phonon mode coupled to the qubits allows for more available states to facilitate the LZ transitions. An analytical formula is obtained to estimate the short time phonon population and produces results in reasonable agreement with numerical calculations. Equipped with the knowledge of the photon-assisted LZ transitions in the system, we can precisely manipulate the qubit state and successfully generate the qubit dynamics with a square-wave pattern by applying driving fields to both qubits, opening up new venues to manipulate the states of qubits and photons in quantum information devices and quantum computers.
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Affiliation(s)
- Fulu Zheng
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, D-01187 Dresden, Germany
| | - Yuejun Shen
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
| | - Kewei Sun
- School of Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Yang Zhao
- Division of Materials Science, Nanyang Technological University, Singapore 639798, Singapore
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12
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Yang B, He B, Wan J, Kubal S, Zhao Y. Applications of neural networks to dynamics simulation of Landau-Zener transitions. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2019.110509] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Kervinen M, Ramírez-Muñoz JE, Välimaa A, Sillanpää MA. Landau-Zener-Stückelberg Interference in a Multimode Electromechanical System in the Quantum Regime. PHYSICAL REVIEW LETTERS 2019; 123:240401. [PMID: 31922814 DOI: 10.1103/physrevlett.123.240401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Indexed: 06/10/2023]
Abstract
The studies of mechanical resonators in the quantum regime not only provide insight into the fundamental nature of quantum mechanics of massive objects, but also introduce promising platforms for novel hybrid quantum technologies. Here we demonstrate a configurable interaction between a superconducting qubit and many acoustic modes in the quantum regime. Specifically, we show how consecutive Landau-Zener-Stückelberg (LZS) tunneling type of transitions, which take place when a system is tuned through an avoided crossing of the coupled energy levels, interfere in a multimode system. The work progresses experimental LZS interference to cover a new class of systems where the coupled levels are those of a quantum two-level system interacting with a multitude of mechanical oscillators. The work opens up applications in controlling multiple acoustic modes via parametric modulation.
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Affiliation(s)
- Mikael Kervinen
- Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland
| | - Jhon E Ramírez-Muñoz
- Departamento de Física, Universidad Nacional de Colombia, 111321 Bogotá, Colombia
| | - Alpo Välimaa
- Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland
| | - Mika A Sillanpää
- Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 AALTO, Finland
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14
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Rol MA, Battistel F, Malinowski FK, Bultink CC, Tarasinski BM, Vollmer R, Haider N, Muthusubramanian N, Bruno A, Terhal BM, DiCarlo L. Fast, High-Fidelity Conditional-Phase Gate Exploiting Leakage Interference in Weakly Anharmonic Superconducting Qubits. PHYSICAL REVIEW LETTERS 2019; 123:120502. [PMID: 31633950 DOI: 10.1103/physrevlett.123.120502] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Indexed: 06/10/2023]
Abstract
Conditional-phase (cz) gates in transmons can be realized by flux pulsing computational states towards resonance with noncomputational ones. We present a 40 ns cz gate based on a bipolar flux pulse suppressing leakage (0.1%) by interference and approaching the speed limit set by exchange coupling. This pulse harnesses a built-in echo to enhance fidelity (99.1%) and is robust to long-timescale distortion in the flux-control line, ensuring repeatability. Numerical simulations matching experiment show that fidelity is limited by high-frequency dephasing and leakage by short-timescale distortion.
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Affiliation(s)
- M A Rol
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - F Battistel
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - F K Malinowski
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - C C Bultink
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - B M Tarasinski
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - R Vollmer
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - N Haider
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Netherlands Organisation for Applied Scientic Research (TNO), P.O. Box 96864, 2509 JG The Hague, The Netherlands
| | - N Muthusubramanian
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - A Bruno
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
| | - B M Terhal
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- JARA Institute for Quantum Information, Forschungszentrum Juelich, D-52425 Juelich, Germany
| | - L DiCarlo
- QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
- Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands
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15
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Zhang X, Li HO, Cao G, Xiao M, Guo GC, Guo GP. Semiconductor quantum computation. Natl Sci Rev 2019; 6:32-54. [PMID: 34691830 PMCID: PMC8291422 DOI: 10.1093/nsr/nwy153] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 11/05/2018] [Accepted: 12/18/2018] [Indexed: 11/12/2022] Open
Abstract
Semiconductors, a significant type of material in the information era, are becoming more and more powerful in the field of quantum information. In recent decades, semiconductor quantum computation was investigated thoroughly across the world and developed with a dramatically fast speed. The research varied from initialization, control and readout of qubits, to the architecture of fault-tolerant quantum computing. Here, we first introduce the basic ideas for quantum computing, and then discuss the developments of single- and two-qubit gate control in semiconductors. Up to now, the qubit initialization, control and readout can be realized with relatively high fidelity and a programmable two-qubit quantum processor has even been demonstrated. However, to further improve the qubit quality and scale it up, there are still some challenges to resolve such as the improvement of the readout method, material development and scalable designs. We discuss these issues and introduce the forefronts of progress. Finally, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation, we anticipate that semiconductor quantum computation may develop fast and will have a huge impact on our lives in the near future.
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Affiliation(s)
- Xin Zhang
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Hai-Ou Li
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Gang Cao
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Ming Xiao
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Guo-Ping Guo
- Key Laboratory of Quantum Information, CAS, University of Science and Technology of China, Hefei 230026, China
- Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
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16
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Integrated silicon qubit platform with single-spin addressability, exchange control and single-shot singlet-triplet readout. Nat Commun 2018; 9:4370. [PMID: 30375392 PMCID: PMC6207676 DOI: 10.1038/s41467-018-06039-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Accepted: 07/27/2018] [Indexed: 11/28/2022] Open
Abstract
Silicon quantum dot spin qubits provide a promising platform for large-scale quantum computation because of their compatibility with conventional CMOS manufacturing and the long coherence times accessible using 28Si enriched material. A scalable error-corrected quantum processor, however, will require control of many qubits in parallel, while performing error detection across the constituent qubits. Spin resonance techniques are a convenient path to parallel two-axis control, while Pauli spin blockade can be used to realize local parity measurements for error detection. Despite this, silicon qubit implementations have so far focused on either single-spin resonance control, or control and measurement via voltage-pulse detuning in the two-spin singlet–triplet basis, but not both simultaneously. Here, we demonstrate an integrated device platform incorporating a silicon metal-oxide-semiconductor double quantum dot that is capable of single-spin addressing and control via electron spin resonance, combined with high-fidelity spin readout in the singlet-triplet basis. Significant progress has been made developing the different methods needed for a spin-based quantum computer but the challenge of integrating them remains. Fogarty et al. present a system with single-spin addressability, spin-spin interactions and high-fidelity readout that provides a scalable foundation for error-corrected devices.
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17
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Zhao X, Hu X. Toward high-fidelity coherent electron spin transport in a GaAs double quantum dot. Sci Rep 2018; 8:13968. [PMID: 30228299 PMCID: PMC6143546 DOI: 10.1038/s41598-018-31879-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/14/2018] [Indexed: 11/18/2022] Open
Abstract
In this paper, we investigate how to achieve high-fidelity electron spin transport in a GaAs double quantum dot. Our study examines fidelity loss in spin transport from multiple perspectives. We first study incoherent fidelity loss due to hyperfine and spin-orbit interaction. We calculate fidelity loss due to the random Overhauser field from hyperfine interaction, and spin relaxation rate due to spin-orbit interaction in a wide range of experimental parameters with a focus on the occurrence of spin hot spots. A safe parameter regime is identified in order to avoid these spin hot spots. We then analyze systematic errors due to non-adiabatic transitions in the Landau-Zener process of sweeping the interdot detuning, and propose a scheme to take advantage of possible Landau-Zener-Stückelberg interference to achieve high-fidelity spin transport at a higher speed. At last, we study another systematic error caused by the correction to the electron g-factor from the double dot potential, which can lead to a notable phase error. In all, our results should provide a useful guidance for future experiments on coherent electron spin transport.
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Affiliation(s)
- Xinyu Zhao
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York, 14260-1500, USA
| | - Xuedong Hu
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York, 14260-1500, USA.
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18
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Koski JV, Landig AJ, Pályi A, Scarlino P, Reichl C, Wegscheider W, Burkard G, Wallraff A, Ensslin K, Ihn T. Floquet Spectroscopy of a Strongly Driven Quantum Dot Charge Qubit with a Microwave Resonator. PHYSICAL REVIEW LETTERS 2018; 121:043603. [PMID: 30095954 DOI: 10.1103/physrevlett.121.043603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Indexed: 06/08/2023]
Abstract
We experimentally investigate a strongly driven GaAs double quantum dot charge qubit weakly coupled to a superconducting microwave resonator. The Floquet states emerging from strong driving are probed by tracing the qubit-resonator resonance condition. In this way, we probe the resonance of a qubit that is driven in an adiabatic, a nonadiabatic, or an intermediate rate, showing distinct quantum features of multiphoton processes and a fringe pattern similar to Landau-Zener-Stückelberg interference. Our resonant detection scheme enables the investigation of novel features when the drive frequency is comparable to the resonator frequency. Models based on the adiabatic approximation, rotating wave approximation, and Floquet theory explain our experimental observations.
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Affiliation(s)
- J V Koski
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - A J Landig
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - A Pályi
- Department of Physics, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
- MTA-BME Exotic Quantum Phases "Momentum" Research Group, Budapest University of Technology and Economics, H-1111 Budapest, Hungary
| | - P Scarlino
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - C Reichl
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - W Wegscheider
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - G Burkard
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - A Wallraff
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - K Ensslin
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - T Ihn
- Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland
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19
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Cota E, Ulloa SE. Spin-orbit interaction and controlled singlet-triplet dynamics in silicon double quantum dots. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:295301. [PMID: 29873301 DOI: 10.1088/1361-648x/aacabc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We undertake a theoretical study of the role of spin orbit interactions in a silicon double quantum dot. We propose that an accurate estimate of the strength of this interaction can be obtained through the study of the return probability of the double occupation singlet state in a magnetic field, as the system is gated dynamically across the relevant states in the low energy two-electron manifold. Landau-Zener type of processes involving appropriate control of voltage pulses across neighboring avoided crossings in the energy spectrum of the system are utilized to explore the system dynamics. Our description takes into account Zeeman splitting, intervalley mixing and spin-orbit interaction present in the structure. Using a density matrix equation of motion approach, we carry out numerical calculations for the return probability of the double occupation singlet state. The analysis in terms of Landau-Zener theory allows the determination of the spin-orbit coupling strength for different Zeeman splitting regimes.
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Affiliation(s)
- Ernesto Cota
- Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada, Baja California 22800, Mexico
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20
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Coherent transfer of electron spin correlations assisted by dephasing noise. Nat Commun 2018; 9:2133. [PMID: 29849025 PMCID: PMC5976655 DOI: 10.1038/s41467-018-04544-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/03/2018] [Indexed: 12/05/2022] Open
Abstract
Quantum coherence of superposed states, especially of entangled states, is indispensable for many quantum technologies. However, it is vulnerable to environmental noises, posing a fundamental challenge in solid-state systems including spin qubits. Here we show a scheme of entanglement engineering where pure dephasing assists the generation of quantum entanglement at distant sites in a chain of electron spins confined in semiconductor quantum dots. One party of an entangled spin pair, prepared at a single site, is transferred to the next site and then adiabatically swapped with a third spin using a transition across a multi-level avoided crossing. This process is accelerated by the noise-induced dephasing through a variant of the quantum Zeno effect, without sacrificing the coherence of the entangled state. Our finding brings insight into the spin dynamics in open quantum systems coupled to noisy environments, opening an avenue to quantum state manipulation utilizing decoherence effects. Methods for coherently transferring quantum states are needed in order to develop larger scale quantum devices. Here the authors implement an adiabatic transfer protocol in a triple quantum dot and show that dephasing noise can accelerate the process while maintaining the coherence of the transferred state.
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21
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Bogan A, Studenikin S, Korkusinski M, Gaudreau L, Zawadzki P, Sachrajda AS, Tracy L, Reno J, Hargett T. Landau-Zener-Stückelberg-Majorana Interferometry of a Single Hole. PHYSICAL REVIEW LETTERS 2018; 120:207701. [PMID: 29864336 DOI: 10.1103/physrevlett.120.207701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Indexed: 06/08/2023]
Abstract
We perform Landau-Zener-Stückelberg-Majorana (LZSM) spectroscopy on a system with strong spin-orbit interaction (SOI), realized as a single hole confined in a gated double quantum dot. Analogous to electron systems, at a magnetic field B=0 and high modulation frequencies, we observe photon-assisted tunneling between dots, which smoothly evolves into the typical LZSM funnel-shaped interference pattern as the frequency is decreased. In contrast to electrons, the SOI enables an additional, efficient spin-flip interdot tunneling channel, introducing a distinct interference pattern at finite B. Magnetotransport spectra at low-frequency LZSM driving show the two channels to be equally coherent. High-frequency LZSM driving reveals complex photon-assisted tunneling pathways, both spin conserving and spin flip, which form closed loops at critical magnetic fields. In one such loop, an arbitrary hole spin state is inverted, opening the way toward its all-electrical manipulation.
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Affiliation(s)
- Alex Bogan
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Sergei Studenikin
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Marek Korkusinski
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Louis Gaudreau
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Piotr Zawadzki
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Andy S Sachrajda
- Emerging Technology Division, National Research Council, Ottawa, Canada K1A0R6
| | - Lisa Tracy
- Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - John Reno
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
| | - Terry Hargett
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, USA
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22
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Landau-Zener-Stückelberg interference in coherent charge oscillations of a one-electron double quantum dot. Sci Rep 2018; 8:5491. [PMID: 29615670 PMCID: PMC5882656 DOI: 10.1038/s41598-018-23468-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 03/13/2018] [Indexed: 11/09/2022] Open
Abstract
Landau-Zener (LZ) transition has received renewed interest as an alternative approach to control single-qubit states. An LZ transition occurs when a system passes through an avoided crossing that arises from quantum mechanical coupling of two levels, taking the system to a coherent superposition of the two states. Then, multiple LZ transitions induce interference known as Landau-Zener-Stückelberg (LZS) interference whose amplitude strongly depends on the velocity or adiabaticity of the passage. Here, we study the roles of LZ transitions and LZS interference in coherent charge oscillations of a one-electron semiconductor double quantum dot by time-domain experiments using standard rectangular voltage pulses. By employing density matrix simulations, we show that, in the standard setup using rectangular pulses, even a small distortion of the pulse can give rise to LZ transitions and hence LZS interference, which significantly enhances the measured oscillation amplitude. We further show experimentally that the nature of the coherent charge oscillations changes from Rabi-type to LZS oscillations with increasing pulse distortion. Our results thus demonstrate that it is essential to take into account LZS interference for both precise control of charge qubits and correct interpretation of measurement results.
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23
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Zhang SS, Gao W, Cheng H, You L, Liu HP. Symmetry-Breaking Assisted Landau-Zener Transitions in Rydberg Atoms. PHYSICAL REVIEW LETTERS 2018; 120:063203. [PMID: 29481261 DOI: 10.1103/physrevlett.120.063203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 05/12/2017] [Indexed: 06/08/2023]
Abstract
We report the observation of a controlled Landau-Zener transition (LZT) in Rydberg atoms by breaking the symmetry of the underlying Hamiltonian. For a nonhydrogenic Rydberg atom inside a changing electric (F) field, a LZT occurs between the avoided crossing energy levels of neighboring Rydberg states only for a sufficiently high changing rate. If a transverse magnetic (B) field is applied as we implement, the atomic level symmetry is broken, which causes the Stark manifolds denoted by a different |m| (m is the magnetic quantum number) to interact with each other. The mixed state levels end up pushing the adiabatically repelled target states closer and additionally they serve as stepping stones for the sequential LZTs between the neighboring sublevels. Such a feature significantly decreases the changing rate required for an efficient LZT inside a pure electric field. We report experimental observations that support the above scenario. It opens a versatile approach for engineering a controlled LZT in more general systems.
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Affiliation(s)
- S S Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - W Gao
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - H Cheng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - L You
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - H P Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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24
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Nalbach P, Klinkenberg N, Palm T, Müller N. Environmental rocking ratchet: Environmental rectification by a harmonically driven avoided crossing. Phys Rev E 2018; 96:042134. [PMID: 29347519 DOI: 10.1103/physreve.96.042134] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Indexed: 11/07/2022]
Abstract
We propose a rocking ratchet designed as a symmetric quantum two-state system driven by a single periodic harmonic force and influenced symmetrically by thermal fluctuations. We show that the necessary broken symmetry can dynamically be achieved by a thermal environment that couples to the energy difference between the two states and the tunnel coupling between them. The quantum two-state system is driven by the harmonic periodic drive through its avoided crossing. The correspondingly driven dissipative quantum dynamics results on average in a finite population difference between both states. This then causes directed particle transport.
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Affiliation(s)
- P Nalbach
- Fachbereich Wirtschaft & Informationstechnik, Westfälische Hochschule, Münsterstrasse 265, 46397 Bocholt, Germany
| | - N Klinkenberg
- Fachbereich Wirtschaft & Informationstechnik, Westfälische Hochschule, Münsterstrasse 265, 46397 Bocholt, Germany
| | - T Palm
- Fachbereich Wirtschaft & Informationstechnik, Westfälische Hochschule, Münsterstrasse 265, 46397 Bocholt, Germany.,I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, 20355 Hamburg, Germany
| | - N Müller
- Fachbereich Wirtschaft & Informationstechnik, Westfälische Hochschule, Münsterstrasse 265, 46397 Bocholt, Germany
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25
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Martins F, Malinowski FK, Nissen PD, Fallahi S, Gardner GC, Manfra MJ, Marcus CM, Kuemmeth F. Negative Spin Exchange in a Multielectron Quantum Dot. PHYSICAL REVIEW LETTERS 2017; 119:227701. [PMID: 29286778 DOI: 10.1103/physrevlett.119.227701] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Indexed: 06/07/2023]
Abstract
We use a one-electron quantum dot as a spectroscopic probe to study the spin properties of a gate-controlled multielectron GaAs quantum dot at the transition between odd and even occupation numbers. We observe that the multielectron ground-state transitions from spin-1/2-like to singletlike to tripletlike as we increase the detuning towards the next higher charge state. The sign reversal in the inferred exchange energy persists at zero magnetic field, and the exchange strength is tunable by gate voltages and in-plane magnetic fields. Complementing spin leakage spectroscopy data, the inspection of coherent multielectron spin exchange oscillations provides further evidence for the sign reversal and, inferentially, for the importance of nontrivial multielectron spin exchange correlations.
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Affiliation(s)
- Frederico Martins
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Filip K Malinowski
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Peter D Nissen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Saeed Fallahi
- Department of Physics and Astronomy, Station Q Purdue, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Geoffrey C Gardner
- Department of Physics and Astronomy, Station Q Purdue, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Michael J Manfra
- Department of Physics and Astronomy, Station Q Purdue, and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering and School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Charles M Marcus
- Center for Quantum Devices and Station Q Copenhagen, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ferdinand Kuemmeth
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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26
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Schoenfield JS, Freeman BM, Jiang H. Coherent manipulation of valley states at multiple charge configurations of a silicon quantum dot device. Nat Commun 2017; 8:64. [PMID: 28680042 PMCID: PMC5498670 DOI: 10.1038/s41467-017-00073-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/31/2017] [Indexed: 11/09/2022] Open
Abstract
Qubits based on silicon quantum dots are emerging as leading candidates for the solid-state implementation of quantum information processing. In silicon, valley states represent a degree of freedom in addition to spin and charge. Characterizing and controlling valley states is critical for the encoding and read-out of electrons-in-silicon-based qubits. Here, we report the coherent manipulation of a qubit, which is based on the two valley states of an electron confined in a silicon quantum dot. We carry out valley qubit operations at multiple charge configurations of the double quantum dot device. The dependence of coherent oscillations on pulse excitation level and duration allows us to map out the energy dispersion as a function of detuning as well as the phase coherence time of the valley qubit. The coherent manipulation also provides a method of measuring valley splittings that are too small to probe with conventional methods. Silicon quantum dots provide a promising platform for quantum computing based on manipulation of electron degrees of freedom in a well-characterized environment. Here, the authors demonstrate coherent control of electron valley states, yielding an accurate determination of the valley splitting.
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Affiliation(s)
- Joshua S Schoenfield
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, 90095, USA
| | - Blake M Freeman
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, 90095, USA
| | - HongWen Jiang
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California, 90095, USA.
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27
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Chen B, Wang B, Cao G, Li H, Xiao M, Guo G. Enhanced readout of spin states in double quantum dot. Sci Bull (Beijing) 2017; 62:712-716. [PMID: 36659443 DOI: 10.1016/j.scib.2017.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 01/21/2023]
Abstract
We investigate a spin-to-charge conversion mechanism which maps the spin singlet and triplet states to two charge states differing by one electron mediated by an intermediate metastable charge state. This mechanism allows us to observe fringes in the spin-unblocked region beyond the triplet transition line in the measurement of the exchange oscillations between singlet and triplet states in a four-electron double quantum dot. Moreover, these fringes are amplified and π-phase shifted, compared with those in the spin blockade region. Unlike the signal enhancement mechanism reported before which produces similar effects, this mechanism only requires one dot coupling to the lead, which is a commonly encountered case especially in imperfect devices. Besides, the crucial tunnel rate asymmetry is provided by the dependence on spin state, not by the asymmetric couplings to the leads. We also design a scheme to control the amplification process, which enables us to extract the relevant time parameters. This mechanism will have potential applications in future investigations of spin qubits.
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Affiliation(s)
- Baobao Chen
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Baochuan Wang
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Gang Cao
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
| | - Haiou Li
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Ming Xiao
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China
| | - Guoping Guo
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China; Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
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28
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Korkusinski M, Studenikin SA, Aers G, Granger G, Kam A, Sachrajda AS. Landau-Zener-Stückelberg Interferometry in Quantum Dots with Fast Rise Times: Evidence for Coherent Phonon Driving. PHYSICAL REVIEW LETTERS 2017; 118:067701. [PMID: 28234547 DOI: 10.1103/physrevlett.118.067701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Indexed: 06/06/2023]
Abstract
Manipulating qubits via electrical pulses in a piezoelectric material such as GaAs can be expected to generate incidental acoustic phonons. In this Letter we determine theoretically and experimentally the consequences of these phonons for semiconductor spin qubits using Landau-Zener-Stückelberg interferometry. Theoretical calculations predict that phonons in the presence of the spin-orbit interaction produce both phonon-Rabi fringes and accelerated evolution at the singlet-triplet anticrossing. Observed features confirm the influence of these mechanisms. Additionally, evidence is found that the pulsed gates themselves act as phonon cavities increasing the influence of phonons under specific resonant conditions.
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Affiliation(s)
- M Korkusinski
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - S A Studenikin
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - G Aers
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - G Granger
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - A Kam
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
| | - A S Sachrajda
- Security and Disruptive Technologies, National Research Council Canada, Ottawa, K1A 0R6, Canada
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29
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Yamaguchi M, Yuge T, Ogawa T. Markovian quantum master equation beyond adiabatic regime. Phys Rev E 2017; 95:012136. [PMID: 28208408 DOI: 10.1103/physreve.95.012136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Indexed: 06/06/2023]
Abstract
By introducing a temporal change time scale τ_{A}(t) for the time-dependent system Hamiltonian, a general formulation of the Markovian quantum master equation is given to go well beyond the adiabatic regime. In appropriate situations, the framework is well justified even if τ_{A}(t) is faster than the decay time scale of the bath correlation function. An application to the dissipative Landau-Zener model demonstrates this general result. The findings are applicable to a wide range of fields, providing a basis for quantum control beyond the adiabatic regime.
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Affiliation(s)
- Makoto Yamaguchi
- Center for Emergent Matter Science, RIKEN, Wakoshi, Saitama 351-0198, Japan
| | - Tatsuro Yuge
- Department of Physics, Shizuoka University, Shizuoka 422-8529, Japan
| | - Tetsuo Ogawa
- Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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30
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Lima LRF, Hernández AR, Pinheiro FA, Lewenkopf C. A 50/50 electronic beam splitter in graphene nanoribbons as a building block for electron optics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:505303. [PMID: 27768605 DOI: 10.1088/0953-8984/28/50/505303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Based on the investigation of the multi-terminal conductance of a system composed of two graphene nanoribbons, in which one is on top of the other and rotated by [Formula: see text], we propose a setup for a 50/50 electronic beam splitter that neither requires large magnetic fields nor ultra low temperatures. Our findings are based on an atomistic tight-binding description of the system and on the Green function method to compute the Landauer conductance. We demonstrate that this system acts as a perfect 50/50 electronic beam splitter, in which its operation can be switched on and off by varying the doping (Fermi energy). We show that this device is robust against thermal fluctuations and long range disorder, as zigzag valley chiral states of the nanoribbons are protected against backscattering. We suggest that the proposed device can be applied as the fundamental element of the Hong-Ou-Mandel interferometer, as well as a building block of many devices in electron optics.
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Affiliation(s)
- Leandro R F Lima
- Instituto de Física, Universidade Federal Fluminense, 24210-346 Niterói, RJ, Brazil
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31
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Gullans MJ, Stehlik J, Liu YY, Eichler C, Petta JR, Taylor JM. Sisyphus Thermalization of Photons in a Cavity-Coupled Double Quantum Dot. PHYSICAL REVIEW LETTERS 2016; 117:056801. [PMID: 27517784 PMCID: PMC5245799 DOI: 10.1103/physrevlett.117.056801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Indexed: 06/06/2023]
Abstract
We investigate the nonclassical states of light that emerge in a microwave resonator coupled to a periodically driven electron in a nanowire double quantum dot (DQD). Under certain drive configurations, we find that the resonator approaches a thermal state at the temperature of the surrounding substrate with a chemical potential given by a harmonic of the drive frequency. Away from these thermal regions we find regions of gain and loss, where the system can lase, or regions where the DQD acts as a single-photon source. These effects are observable in current devices and have broad utility for quantum optics with microwave photons.
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Affiliation(s)
- M J Gullans
- Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
| | - J Stehlik
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Y-Y Liu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - C Eichler
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - J R Petta
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - J M Taylor
- Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Joint Center for Quantum Information and Computer Science, University of Maryland, College Park, Maryland 20742, USA
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32
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Uppu R, Wolterink TAW, Tentrup TBH, Pinkse PWH. Quantum optics of lossy asymmetric beam splitters. OPTICS EXPRESS 2016; 24:16440-16449. [PMID: 27464096 DOI: 10.1364/oe.24.016440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We theoretically investigate quantum interference of two single photons at a lossy asymmetric beam splitter, the most general passive 2×2 optical circuit. The losses in the circuit result in a non-unitary scattering matrix with a non-trivial set of constraints on the elements of the scattering matrix. Our analysis using the noise operator formalism shows that the loss allows tunability of quantum interference to an extent not possible with a lossless beam splitter. Our theoretical studies support the experimental demonstrations of programmable quantum interference in highly multimodal systems such as opaque scattering media and multimode fibers.
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33
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Martins F, Malinowski FK, Nissen PD, Barnes E, Fallahi S, Gardner GC, Manfra MJ, Marcus CM, Kuemmeth F. Noise Suppression Using Symmetric Exchange Gates in Spin Qubits. PHYSICAL REVIEW LETTERS 2016; 116:116801. [PMID: 27035316 DOI: 10.1103/physrevlett.116.116801] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate a substantial improvement in the spin-exchange gate using symmetric control instead of conventional detuning in GaAs spin qubits, up to a factor of six increase in the quality factor of the gate. For symmetric operation, nanosecond voltage pulses are applied to the barrier that controls the interdot potential between quantum dots, modulating the exchange interaction while maintaining symmetry between the dots. Excellent agreement is found with a model that separately includes electrical and nuclear noise sources for both detuning and symmetric gating schemes. Unlike exchange control via detuning, the decoherence of symmetric exchange rotations is dominated by rotation-axis fluctuations due to nuclear field noise rather than direct exchange noise.
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Affiliation(s)
- Frederico Martins
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Filip K Malinowski
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Peter D Nissen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Edwin Barnes
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Saeed Fallahi
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Geoffrey C Gardner
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
| | - Michael J Manfra
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907, USA
| | - Charles M Marcus
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Ferdinand Kuemmeth
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
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34
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Gonzalez-Zalba MF, Shevchenko SN, Barraud S, Johansson JR, Ferguson AJ, Nori F, Betz AC. Gate-Sensing Coherent Charge Oscillations in a Silicon Field-Effect Transistor. NANO LETTERS 2016; 16:1614-1619. [PMID: 26866446 DOI: 10.1021/acs.nanolett.5b04356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stückelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ≈ 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology.
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Affiliation(s)
| | - Sergey N Shevchenko
- B.Verkin Institute for Low Temperature Physics and Engineering, Kharkov 61103, Ukraine
- V. Karazin Kharkov National University , Kharkov 61022, Ukraine
- Center for Emergent Matter Science, RIKEN , Wako-shi, Saitama 351-0198, Japan
| | | | - J Robert Johansson
- Center for Emergent Matter Science, RIKEN , Wako-shi, Saitama 351-0198, Japan
| | - Andrew J Ferguson
- Cavendish Laboratory, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Franco Nori
- Center for Emergent Matter Science, RIKEN , Wako-shi, Saitama 351-0198, Japan
- Department of Physics, The University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Andreas C Betz
- Hitachi Cambridge Laboratory, Cambridge CB3 0HE, United Kingdom
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35
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Wang L, Tu T, Gong B, Zhou C, Guo GC. Experimental realization of non-adiabatic universal quantum gates using geometric Landau-Zener-Stückelberg interferometry. Sci Rep 2016; 6:19048. [PMID: 26738875 PMCID: PMC4703957 DOI: 10.1038/srep19048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 12/03/2015] [Indexed: 11/09/2022] Open
Abstract
High fidelity universal gates for quantum bits form an essential ingredient of quantum information processing. In particular, geometric gates have attracted attention because they have a higher intrinsic resistance to certain errors. However, their realization remains a challenge because of the need for complicated quantum control on a multi-level structure as well as meeting the adiabatic condition within a short decoherence time. Here, we demonstrate non-adiabatic quantum operations for a two-level system by applying a well-controlled geometric Landau-Zener-Stückelberg interferometry. By characterizing the gate quality, we also investigate the operation in the presence of realistic dephasing. Furthermore, the result provides an essential model suitable for understanding an interplay of geometric phase and Landau-Zener-Stückelberg process which are well explored separately.
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Affiliation(s)
- Li Wang
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, People's Republic of China
| | - Tao Tu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, People's Republic of China
| | - Bo Gong
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, People's Republic of China
| | - Cheng Zhou
- Department of Physics and Astronomy, University of California at Los Angeles, California 90095, USA
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei 230026, People's Republic of China
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36
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Nichol JM, Harvey SP, Shulman MD, Pal A, Umansky V, Rashba EI, Halperin BI, Yacoby A. Quenching of dynamic nuclear polarization by spin-orbit coupling in GaAs quantum dots. Nat Commun 2015; 6:7682. [PMID: 26184854 PMCID: PMC4518271 DOI: 10.1038/ncomms8682] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 06/01/2015] [Indexed: 11/29/2022] Open
Abstract
The central-spin problem is a widely studied model of quantum decoherence. Dynamic nuclear polarization occurs in central-spin systems when electronic angular momentum is transferred to nuclear spins and is exploited in quantum information processing for coherent spin manipulation. However, the mechanisms limiting this process remain only partially understood. Here we show that spin–orbit coupling can quench dynamic nuclear polarization in a GaAs quantum dot, because spin conservation is violated in the electron–nuclear system, despite weak spin–orbit coupling in GaAs. Using Landau–Zener sweeps to measure static and dynamic properties of the electron spin–flip probability, we observe that the size of the spin–orbit and hyperfine interactions depends on the magnitude and direction of applied magnetic field. We find that dynamic nuclear polarization is quenched when the spin–orbit contribution exceeds the hyperfine, in agreement with a theoretical model. Our results shed light on the surprisingly strong effect of spin–orbit coupling in central-spin systems. Dynamic nuclear polarization is the transfer of electronic angular momentum to nuclear spins and is a potential route for coherently manipulating spin in quantum information. Here, the authors show that spin–orbit coupling can quench dynamic nuclear polarization in a gallium arsenide quantum dot.
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Affiliation(s)
- John M Nichol
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Shannon P Harvey
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Michael D Shulman
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Arijeet Pal
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Vladimir Umansky
- Braun Center for Submicron Research, Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Emmanuel I Rashba
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Bertrand I Halperin
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Amir Yacoby
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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37
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Sun G, Wen X, Gong M, Zhang DW, Yu Y, Zhu SL, Chen J, Wu P, Han S. Observation of coherent oscillation in single-passage Landau-Zener transitions. Sci Rep 2015; 5:8463. [PMID: 25684697 PMCID: PMC4329555 DOI: 10.1038/srep08463] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 01/21/2015] [Indexed: 11/23/2022] Open
Abstract
Landau-Zener transition (LZT) has been explored in a variety of physical systems for coherent population transfer between different quantum states. In recent years, there have been various proposals for applying LZT to quantum information processing because when compared to the methods using ac pulse for coherent population transfer, protocols based on LZT are less sensitive to timing errors. However, the effect of finite range of qubit energy available to LZT based state control operations has not been thoroughly examined. In this work, we show that using the well-known Landau-Zener formula in the vicinity of an avoided energy-level crossing will cause considerable errors due to coherent oscillation of the transition probability in a single-passage LZT experiment. The data agree well with the numerical simulations which take the transient dynamics of LZT into account. These results not only provide a closer view on the issue of finite-time LZT but also shed light on its effects on the quantum state manipulation.
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Affiliation(s)
- Guozhu Sun
- 1] National Laboratory of Solid State Microstructures and Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China [2] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [3] Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
| | - Xueda Wen
- Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Ming Gong
- 1] Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA [2] National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Dan-Wei Zhang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yang Yu
- 1] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China [2] National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Shi-Liang Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Jian Chen
- National Laboratory of Solid State Microstructures and Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Peiheng Wu
- 1] National Laboratory of Solid State Microstructures and Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China [2] Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Siyuan Han
- Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA
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38
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Two-axis control of a singlet-triplet qubit with an integrated micromagnet. Proc Natl Acad Sci U S A 2014; 111:11938-42. [PMID: 25092298 DOI: 10.1073/pnas.1412230111] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The qubit is the fundamental building block of a quantum computer. We fabricate a qubit in a silicon double-quantum dot with an integrated micromagnet in which the qubit basis states are the singlet state and the spin-zero triplet state of two electrons. Because of the micromagnet, the magnetic field difference ΔB between the two sides of the double dot is large enough to enable the achievement of coherent rotation of the qubit's Bloch vector around two different axes of the Bloch sphere. By measuring the decay of the quantum oscillations, the inhomogeneous spin coherence time T2* is determined. By measuring T2* at many different values of the exchange coupling J and at two different values of ΔB, we provide evidence that the micromagnet does not limit decoherence, with the dominant limits on T2* arising from charge noise and from coupling to nuclear spins.
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39
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Dodin A, Garmon S, Simine L, Segal D. Landau-Zener transitions mediated by an environment: Population transfer and energy dissipation. J Chem Phys 2014; 140:124709. [DOI: 10.1063/1.4869519] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Forster F, Petersen G, Manus S, Hänggi P, Schuh D, Wegscheider W, Kohler S, Ludwig S. Characterization of qubit dephasing by Landau-Zener-Stückelberg-Majorana interferometry. PHYSICAL REVIEW LETTERS 2014; 112:116803. [PMID: 24702402 DOI: 10.1103/physrevlett.112.116803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Indexed: 06/03/2023]
Abstract
Controlling coherent interaction at avoided crossings and the dynamics there is at the heart of quantum information processing. A particularly intriguing dynamics is observed in the Landau-Zener regime, where periodic passages through the avoided crossing result in an interference pattern carrying information about qubit properties. In this Letter, we demonstrate a straightforward method, based on steady-state experiments, to obtain all relevant information about a qubit, including complex environmental influences. We use a two-electron charge qubit defined in a lateral double quantum dot as test system and demonstrate a long coherence time of T2 ≃ 200 ns, which is limited by electron-phonon interaction.
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Affiliation(s)
- F Forster
- Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany
| | - G Petersen
- Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany
| | - S Manus
- Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany
| | - P Hänggi
- Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany
| | - D Schuh
- Fakultät für Physik, Universität Regensburg, 93040 Regensburg, Germany
| | - W Wegscheider
- Fakultät für Physik, Universität Regensburg, 93040 Regensburg, Germany and Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland
| | - S Kohler
- Instituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Spain
| | - S Ludwig
- Center for NanoScience & Fakultät für Physik, LMU-Munich, 80539 München, Germany
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41
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Tan X, Zhang DW, Zhang Z, Yu Y, Han S, Zhu SL. Demonstration of geometric Landau-Zener interferometry in a superconducting qubit. PHYSICAL REVIEW LETTERS 2014; 112:027001. [PMID: 24484040 DOI: 10.1103/physrevlett.112.027001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Indexed: 06/03/2023]
Abstract
Geometric quantum manipulation and Landau-Zener interferometry have been separately explored in many quantum systems. In this Letter, we combine these two approaches to study the dynamics of a superconducting phase qubit. We experimentally demonstrate Landau-Zener interferometry based on the pure geometric phases in this solid-state qubit. We observe the interference caused by a pure geometric phase accumulated in the evolution between two consecutive Landau-Zener transitions, while the dynamical phase is canceled out by a spin-echo pulse. The full controllability of the qubit state as a function of the intrinsically robust geometric phase provides a promising approach for quantum state manipulation.
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Affiliation(s)
- Xinsheng Tan
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China and Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Dan-Wei Zhang
- Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006, China
| | - Zhentao Zhang
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Yang Yu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
| | - Siyuan Han
- Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045, USA
| | - Shi-Liang Zhu
- National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China and Laboratory of Quantum Engineering and Quantum Materials, SPTE, South China Normal University, Guangzhou 510006, China
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42
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Zhou J, Huang P, Zhang Q, Wang Z, Tan T, Xu X, Shi F, Rong X, Ashhab S, Du J. Observation of time-domain Rabi oscillations in the Landau-Zener regime with a single electronic spin. PHYSICAL REVIEW LETTERS 2014; 112:010503. [PMID: 24483877 DOI: 10.1103/physrevlett.112.010503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Indexed: 06/03/2023]
Abstract
It is theoretically known that the quantum interference of a long sequence of Landau-Zener transitions can result in Rabi oscillations. Because of its stringent requirements, however, this phenomenon has never been experimentally observed in the time domain. Using a nitrogen-vacancy (NV) center spin in isotopically purified diamond, we observed the Rabi oscillations resulting from more than 100 Landau-Zener processes. Our results demonstrate favorable quantum controllability of NV centers, which could find applications in quantum metrology and quantum information processing.
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Affiliation(s)
- Jingwei Zhou
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Pu Huang
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Qi Zhang
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Zixiang Wang
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Tian Tan
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xiangkun Xu
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Fazhan Shi
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Xing Rong
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - S Ashhab
- Advanced Science Institute, RIKEN, Wako-shi, Saitama 351-0198, Japan and Qatar Environment and Energy Research Institute, Doha, Qatar
| | - Jiangfeng Du
- Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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Bureau-Oxton C, Camirand Lemyre J, Pioro-Ladrière M. Nanofabrication of gate-defined GaAs/AlGaAs lateral quantum dots. J Vis Exp 2013:e50581. [PMID: 24300661 DOI: 10.3791/50581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
A quantum computer is a computer composed of quantum bits (qubits) that takes advantage of quantum effects, such as superposition of states and entanglement, to solve certain problems exponentially faster than with the best known algorithms on a classical computer. Gate-defined lateral quantum dots on GaAs/AlGaAs are one of many avenues explored for the implementation of a qubit. When properly fabricated, such a device is able to trap a small number of electrons in a certain region of space. The spin states of these electrons can then be used to implement the logical 0 and 1 of the quantum bit. Given the nanometer scale of these quantum dots, cleanroom facilities offering specialized equipment- such as scanning electron microscopes and e-beam evaporators- are required for their fabrication. Great care must be taken throughout the fabrication process to maintain cleanliness of the sample surface and to avoid damaging the fragile gates of the structure. This paper presents the detailed fabrication protocol of gate-defined lateral quantum dots from the wafer to a working device. Characterization methods and representative results are also briefly discussed. Although this paper concentrates on double quantum dots, the fabrication process remains the same for single or triple dots or even arrays of quantum dots. Moreover, the protocol can be adapted to fabricate lateral quantum dots on other substrates, such as Si/SiGe.
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Shekhter RI, Entin-Wohlman O, Aharony A. Suspended nanowires as mechanically controlled Rashba spin splitters. PHYSICAL REVIEW LETTERS 2013; 111:176602. [PMID: 24206510 DOI: 10.1103/physrevlett.111.176602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Indexed: 06/02/2023]
Abstract
Suspended nanowires are shown to provide mechanically controlled coherent mixing or splitting of the spin states of transmitted electrons, caused by the Rashba spin-orbit interaction. The sensitivity of the latter to mechanical bending makes the wire a tunable nanoelectromechanical weak link between reservoirs. When the reservoirs are populated with misbalanced "spin-up and spin-down" electrons, the wire becomes a source of split spin currents, which are not associated with electric charge transfer and which do not depend on temperature or driving voltages. The mechanical vibrations of the bended wires allow for additional tunability of these splitters by applying a magnetic field and varying the temperature. Clean metallic carbon nanotubes of a few microns length are good candidates for generating spin conductance of the same order as the charge conductance (divided by e(2)) which would have been induced by electric driving voltages.
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Affiliation(s)
- R I Shekhter
- Department of Physics, Göteborg University, SE-412 96 Göteborg, Sweden
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Ganeshan S, Barnes E, Das Sarma S. Exact classification of Landau-Majorana-Stückelberg-Zener resonances by floquet determinants. PHYSICAL REVIEW LETTERS 2013; 111:130405. [PMID: 24116753 DOI: 10.1103/physrevlett.111.130405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Indexed: 06/02/2023]
Abstract
Recent experiments have shown that Landau-Majorana-Stückelberg-Zener (LMSZ) interferometry is a powerful tool for demonstrating and exploiting quantum coherence not only in atomic systems but also in a variety of solid state quantum systems such as spins in quantum dots, superconducting qubits, and nitrogen vacancy centers in diamond. In this Letter, we propose and develop a general (and, in principle, exact) theoretical formalism to identify and characterize the interference resonances that are the hallmark of LMSZ interferometry. Unlike earlier approaches, our scheme does not require any approximations, allowing us to uncover important and previously unknown features of the resonance structure. We also discuss the experimental observability of our results.
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Affiliation(s)
- Sriram Ganeshan
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
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de Graaf SE, Leppäkangas J, Adamyan A, Danilov AV, Lindström T, Fogelström M, Bauch T, Johansson G, Kubatkin SE. Charge qubit coupled to an intense microwave electromagnetic field in a superconducting Nb device: evidence for photon-assisted quasiparticle tunneling. PHYSICAL REVIEW LETTERS 2013; 111:137002. [PMID: 24116809 DOI: 10.1103/physrevlett.111.137002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Indexed: 06/02/2023]
Abstract
We study a superconducting charge qubit coupled to an intensive electromagnetic field and probe changes in the resonance frequency of the formed dressed states. At large driving strengths, exceeding the qubit energy-level splitting, this reveals the well known Landau-Zener-Stückelberg interference structure of a longitudinally driven two-level system. For even stronger drives, we observe a significant change in the Landau-Zener-Stückelberg pattern and contrast. We attribute this to photon-assisted quasiparticle tunneling in the qubit. This results in the recovery of the qubit parity, eliminating effects of quasiparticle poisoning, and leads to an enhanced interferometric response. The interference pattern becomes robust to quasiparticle poisoning and has a good potential for accurate charge sensing.
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Affiliation(s)
- S E de Graaf
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Goteborg, Sweden
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Medford J, Beil J, Taylor JM, Bartlett SD, Doherty AC, Rashba EI, DiVincenzo DP, Lu H, Gossard AC, Marcus CM. Self-consistent measurement and state tomography of an exchange-only spin qubit. NATURE NANOTECHNOLOGY 2013; 8:654-659. [PMID: 23995458 DOI: 10.1038/nnano.2013.168] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 07/20/2013] [Indexed: 06/02/2023]
Abstract
Quantum-dot spin qubits characteristically use oscillating magnetic or electric fields, or quasi-static Zeeman field gradients, to realize full qubit control. For the case of three confined electrons, exchange interaction between two pairs allows qubit rotation around two axes, hence full control, using only electrostatic gates. Here, we report initialization, full control, and single-shot readout of a three-electron exchange-driven spin qubit. Control via the exchange interaction is fast, yielding a demonstrated 75 qubit rotations in less than 2 ns. Measurement and state tomography are performed using a maximum-likelihood estimator method, allowing decoherence, leakage out of the qubit state space, and measurement fidelity to be quantified. The methods developed here are generally applicable to systems with state leakage, noisy measurements and non-orthogonal control axes.
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Affiliation(s)
- J Medford
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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Ultrafast universal quantum control of a quantum-dot charge qubit using Landau-Zener-Stückelberg interference. Nat Commun 2013; 4:1401. [PMID: 23360992 PMCID: PMC3562462 DOI: 10.1038/ncomms2412] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 12/20/2012] [Indexed: 11/19/2022] Open
Abstract
A basic requirement for quantum information processing is the ability to universally control the state of a single qubit on timescales much shorter than the coherence time. Although ultrafast optical control of a single spin has been achieved in quantum dots, scaling up such methods remains a challenge. Here we demonstrate complete control of the quantum-dot charge qubit on the picosecond scale, orders of magnitude faster than the previously measured electrically controlled charge- or spin-based qubits. We observe tunable qubit dynamics in a charge-stability diagram, in a time domain, and in a pulse amplitude space of the driven pulse. The observations are well described by Landau–Zener–Stückelberg interference. These results establish the feasibility of a full set of all-electrical single-qubit operations. Although our experiment is carried out in a solid-state architecture, the technique is independent of the physical encoding of the quantum information and has the potential for wider applications. Universal control of the state of qubits on timescales much shorter than the coherence time is necessary for quantum computation. The authors demonstrate electrical control of a charge qubit in quantum dots on the picosecond scale, which is orders of magnitude faster than previously reported.
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Ribeiro H, Burkard G. Nuclear spins keep coming back. NATURE MATERIALS 2013; 12:469-471. [PMID: 23695732 DOI: 10.1038/nmat3671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- Hugo Ribeiro
- Department of Physics, University of Basel, Basel, Switzerland.
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