1
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Sasaki K, Abe E. Suppression of Pulsed Dynamic Nuclear Polarization by Many-Body Spin Dynamics. PHYSICAL REVIEW LETTERS 2024; 132:106904. [PMID: 38518331 DOI: 10.1103/physrevlett.132.106904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 02/06/2024] [Indexed: 03/24/2024]
Abstract
We study a mechanism by which nuclear hyperpolarization due to the polarization transfer from a microwave-pulse-controlled electron spin is suppressed. From analytical and numerical calculations of the unitary dynamics of multiple nuclear spins, we uncover that, combined with the formation of the dark state within a cluster of nuclei, coherent higher-order nuclear spin dynamics impose limits on the efficiency of the polarization transfer even in the absence of mundane depolarization processes such as nuclear spin diffusion and relaxation. Furthermore, we show that the influence of the dark state can be partly mitigated by introducing a disentangling operation. Our analysis is applied to the nuclear polarizations observed in ^{13}C nuclei coupled with a single nitrogen-vacancy center in diamond [Randall et al., Science 374, 1474 (2021)SCIEAS0036-807510.1126/science.abk0603]. Our Letter sheds light on collective engineering of nuclear spins as well as future designs of pulsed dynamic nuclear polarization protocols.
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Affiliation(s)
- Kento Sasaki
- Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Eisuke Abe
- RIKEN Center for Quantum Computing, Wako, Saitama 351-0198, Japan
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2
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Kirstein E, Smirnov DS, Zhukov EA, Yakovlev DR, Kopteva NE, Dirin DN, Hordiichuk O, Kovalenko MV, Bayer M. The squeezed dark nuclear spin state in lead halide perovskites. Nat Commun 2023; 14:6683. [PMID: 37865649 PMCID: PMC10590392 DOI: 10.1038/s41467-023-42265-8] [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: 04/25/2023] [Accepted: 10/04/2023] [Indexed: 10/23/2023] Open
Abstract
Coherent many-body states are highly promising for robust quantum information processing. While far-reaching theoretical predictions have been made for various implementations, direct experimental evidence of their appealing properties can be challenging. Here, we demonstrate optical manipulation of the nuclear spin ensemble in the lead halide perovskite semiconductor FAPbBr3 (FA = formamidinium), targeting a long-postulated collective dark state that is insensitive to optical pumping after its build-up. Via optical orientation of localized hole spins we drive the nuclear many-body system into this entangled state, requiring a weak magnetic field of only a few milli-Tesla strength at cryogenic temperatures. During its fast establishment, the nuclear polarization along the optical axis remains small, while the transverse nuclear spin fluctuations are strongly reduced, corresponding to spin squeezing as evidenced by a strong violation of the generalized nuclear squeezing-inequality with ξs < 0.5. The dark state corresponds to an ~35-body entanglement between the nuclei. Dark nuclear spin states can be exploited to store quantum information benefiting from their long-lived many-body coherence and to perform quantum measurements with a precision beyond the standard limit.
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Affiliation(s)
- E Kirstein
- Experimental Physics 2, Department of Physics, TU Dortmund, 44227, Dortmund, Germany.
| | - D S Smirnov
- Ioffe Institute, 194021, St. Petersburg, Russia.
| | - E A Zhukov
- Experimental Physics 2, Department of Physics, TU Dortmund, 44227, Dortmund, Germany
| | - D R Yakovlev
- Experimental Physics 2, Department of Physics, TU Dortmund, 44227, Dortmund, Germany
| | - N E Kopteva
- Experimental Physics 2, Department of Physics, TU Dortmund, 44227, Dortmund, Germany
| | - D N Dirin
- Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
| | - O Hordiichuk
- Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics, Department of Advanced Materials and Surfaces, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
| | - M V Kovalenko
- Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, 8093, Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics, Department of Advanced Materials and Surfaces, Empa - Swiss Federal Laboratories for Materials Science and Technology, 8600, Dübendorf, Switzerland
| | - M Bayer
- Experimental Physics 2, Department of Physics, TU Dortmund, 44227, Dortmund, Germany
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3
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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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4
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Islam S, Shamim S, Ghosh A. Benchmarking Noise and Dephasing in Emerging Electrical Materials for Quantum Technologies. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022:e2109671. [PMID: 35545231 DOI: 10.1002/adma.202109671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 05/01/2022] [Indexed: 06/15/2023]
Abstract
As quantum technologies develop, a specific class of electrically conducting materials is rapidly gaining interest because they not only form the core quantum-enabled elements in superconducting qubits, semiconductor nanostructures, or sensing devices, but also the peripheral circuitry. The phase coherence of the electronic wave function in these emerging materials will be crucial when incorporated in the quantum architecture. The loss of phase memory, or dephasing, occurs when a quantum system interacts with the fluctuations in the local electromagnetic environment, which manifests in "noise" in the electrical conductivity. Hence, characterizing these materials and devices therefrom, for quantum applications, requires evaluation of both dephasing and noise, although there are very few materials where these properties are investigated simultaneously. Here, the available data on magnetotransport and low-frequency fluctuations in electrical conductivity are reviewed to benchmark the dephasing and noise. The focus is on new materials that are of direct interest to quantum technologies. The physical processes causing dephasing and noise in these systems are elaborated, the impact of both intrinsic and extrinsic parameters from materials synthesis and devices realization are evaluated, and it is hoped that a clearer pathway to design and characterize both material and devices for quantum applications is thus provided.
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Affiliation(s)
- Saurav Islam
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India
| | - Saquib Shamim
- Experimentelle Physik III, Physikalisches Institut, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
- Institute for Topological Insulators, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Arindam Ghosh
- Department of Physics, Indian Institute of Science, Bengaluru, 560012, India
- Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru, 560012, India
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5
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Shumilin AV, Smirnov DS. Nuclear Spin Dynamics, Noise, Squeezing, and Entanglement in Box Model. PHYSICAL REVIEW LETTERS 2021; 126:216804. [PMID: 34114866 DOI: 10.1103/physrevlett.126.216804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/24/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
We obtain a compact analytical solution for the nonlinear equation for the nuclear spin dynamics in the central spin box model in the limit of many nuclear spins. The total nuclear spin component along the external magnetic field is conserved and the two perpendicular components precess or oscillate depending on the electron spin polarization, with the frequency, determined by the nuclear spin polarization. As applications of our solution, we calculate the nuclear spin noise spectrum and describe the effects of nuclear spin squeezing and many body entanglement in the absence of a system excitation.
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Affiliation(s)
| | - D S Smirnov
- Ioffe Institute, 194021 St. Petersburg, Russia
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6
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de Leon NP, Itoh KM, Kim D, Mehta KK, Northup TE, Paik H, Palmer BS, Samarth N, Sangtawesin S, Steuerman DW. Materials challenges and opportunities for quantum computing hardware. Science 2021; 372:372/6539/eabb2823. [PMID: 33859004 DOI: 10.1126/science.abb2823] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Quantum computing hardware technologies have advanced during the past two decades, with the goal of building systems that can solve problems that are intractable on classical computers. The ability to realize large-scale systems depends on major advances in materials science, materials engineering, and new fabrication techniques. We identify key materials challenges that currently limit progress in five quantum computing hardware platforms, propose how to tackle these problems, and discuss some new areas for exploration. Addressing these materials challenges will require scientists and engineers to work together to create new, interdisciplinary approaches beyond the current boundaries of the quantum computing field.
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Affiliation(s)
- Nathalie P de Leon
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, Yokohama 223-8522, Japan
| | - Dohun Kim
- Department of Physics and Astronomy and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Karan K Mehta
- Department of Physics, Institute for Quantum Electronics, ETH Zürich, 8092 Zürich, Switzerland
| | - Tracy E Northup
- Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria
| | - Hanhee Paik
- IBM Quantum, IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, USA.
| | - B S Palmer
- Laboratory for Physical Sciences, University of Maryland, College Park, MD 20740, USA.,Quantum Materials Center, University of Maryland, College Park, MD 20742, USA
| | - N Samarth
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Sorawis Sangtawesin
- School of Physics and Center of Excellence in Advanced Functional Materials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - D W Steuerman
- Kavli Foundation, 5715 Mesmer Avenue, Los Angeles, CA 90230, USA
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7
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Zhu XY, Tu T, Guo AL, Zhou ZQ, Guo GC, Li CF. Spin-photon module for scalable network architecture in quantum dots. Sci Rep 2020; 10:5063. [PMID: 32193481 PMCID: PMC7081348 DOI: 10.1038/s41598-020-61976-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 03/05/2020] [Indexed: 11/13/2022] Open
Abstract
Reliable information transmission between spatially separated nodes is fundamental to a network architecture for scalable quantum technology. Spin qubit in semiconductor quantum dots is a promising candidate for quantum information processing. However, there remains a challenge to design a practical path from the existing experiments to scalable quantum processor. Here we propose a module consisting of spin singlet-triplet qubits and single microwave photons. We show a high degree of control over interactions between the spin qubit and the quantum light field can be achieved. Furthermore, we propose preparation of a shaped single photons with an efficiency of 98%, and deterministic quantum state transfer and entanglement generation between remote nodes with a high fidelity of 90%. This spin-photon module has met the threshold of particular designed error-correction protocols, thus provides a feasible approach towards scalable quantum network architecture.
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Affiliation(s)
- Xing-Yu Zhu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, P.R. China
| | - Tao Tu
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, P.R. China. .,Department of Physics and Astronomy, University of California at Los Angeles, California, 90095, USA.
| | - Ao-Lin Guo
- Department of Physics and Astronomy, University of California at Los Angeles, California, 90095, USA
| | - Zong-Quan Zhou
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, P.R. China.
| | - Guang-Can Guo
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, P.R. China
| | - Chuan-Feng Li
- Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, 230026, P.R. China.
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8
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Gangloff DA, Éthier-Majcher G, Lang C, Denning EV, Bodey JH, Jackson DM, Clarke E, Hugues M, Le Gall C, Atatüre M. Quantum interface of an electron and a nuclear ensemble. Science 2019; 364:62-66. [DOI: 10.1126/science.aaw2906] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 02/08/2019] [Indexed: 11/02/2022]
Abstract
Coherent excitation of an ensemble of quantum objects underpins quantum many-body phenomena and offers the opportunity to realize a memory that stores quantum information. Thus far, a deterministic and coherent interface between a spin qubit and such an ensemble has remained elusive. In this study, we first used an electron to cool the mesoscopic nuclear spin ensemble of a semiconductor quantum dot to the nuclear sideband–resolved regime. We then implemented an all-optical approach to access individual quantized electronic-nuclear spin transitions. Lastly, we performed coherent optical rotations of a single collective nuclear spin excitation—a spin wave. These results constitute the building blocks of a dedicated local memory per quantum-dot spin qubit and promise a solid-state platform for quantum-state engineering of isolated many-body systems.
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9
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Ramanayaka AN, Tang K, Hagmann JA, Kim HS, Simons DS, Richter CA, Pomeroy JM. Use of quantum effects as potential qualifying metrics for "quantum grade silicon". AIP ADVANCES 2019; 9:10.1063/1.5128098. [PMID: 38680503 PMCID: PMC11047298 DOI: 10.1063/1.5128098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2024]
Abstract
Across solid state quantum information, materials deficiencies limit performance through enhanced relaxation, charge defect motion or isotopic spin noise. While classical measurements of device performance provide cursory guidance, specific qualifying metrics and measurements applicable to quantum devices are needed. For quantum applications, new materials metrics, e.g., enrichment, are needed, while existing, classical metrics like mobility might be relaxed compared to conventional electronics. In this work, we examine locally grown silicon superior in enrichment, but inferior in chemical purity compared to commercial-silicon, as part of an effort to underpin the materials standards needed for quantum grade silicon and establish a standard approach for intercomparison of these materials. We use a custom, mass-selected ion beam deposition technique, which has produced isotopic enrichment levels up to 99.99998 % 28Si, to isotopically enrich 28Si, but with chemical purity > 99.97% due the MBE techniques used. From this epitaxial silicon, we fabricate top-gated Hall bar devices simultaneously on the 28Si and on the adjacent natural abundance Si substrate for intercomparison. Using standard-methods, we measure maximum mobilities of ≈ ( 1740 ± 2 ) cm 2 / ( V ⋅ s ) at an electron density of ( 2.7 × 10 12 ± 3 × 10 8 ) cm-2 and ≈ ( 6040 ± 3 ) cm 2 / ( V ⋅ s ) at an electron density of ( 1.2 × 10 12 ± 5 × 10 8 ) cm-2 at T = 1.9 K for devices fabricated on 28Si and natSi, respectively. For magnetic fields B > 2 T, both devices demonstrate well developed Shubnikov-de Haas (SdH) oscillations in the longitudinal magnetoresistance. This provides transport characteristics of isotopically enriched 28Si, and will serve as a benchmark for classical transport of 28Si at its current state, and low temperature, epitaxially grown Si for quantum devices more generally.
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Affiliation(s)
- A. N. Ramanayaka
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - Ke Tang
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - J. A. Hagmann
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
| | - Hyun-Soo Kim
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA
| | - D. S. Simons
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
| | - C. A. Richter
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
| | - J. M. Pomeroy
- National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA
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10
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Zhukov EA, Kirstein E, Kopteva NE, Heisterkamp F, Yugova IA, Korenev VL, Yakovlev DR, Pawlis A, Bayer M, Greilich A. Discretization of the total magnetic field by the nuclear spin bath in fluorine-doped ZnSe. Nat Commun 2018; 9:1941. [PMID: 29769536 PMCID: PMC5955946 DOI: 10.1038/s41467-018-04359-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/19/2018] [Indexed: 11/17/2022] Open
Abstract
The coherent spin dynamics of fluorine donor-bound electrons in ZnSe induced by pulsed optical excitation is studied in a perpendicular applied magnetic field. The Larmor precession frequency serves as a measure for the total magnetic field exerted onto the electron spins and, surprisingly, does not increase linearly with the applied field, but shows a step-like behavior with pronounced plateaus, given by multiples of the laser repetition rate. This discretization occurs by a feedback mechanism in which the electron spins polarize the nuclear spins, which in turn generate a local Overhauser field adjusting the total magnetic field accordingly. Varying the optical excitation power, we can control the plateaus, in agreement with our theoretical model. From this model, we trace the observed discretization to the optically induced Stark field, which causes the dynamic nuclear polarization. Understanding the electron and nuclear spin interactions is essential to the application of quantum information devices. Here the authors report a step-like electron Larmor frequency versus external magnetic field due to the discretization of the total magnetic field by the nuclear spin bath in ZnSe:F.
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Affiliation(s)
- E A Zhukov
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany
| | - E Kirstein
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany
| | - N E Kopteva
- Physical Faculty of St. Petersburg State University, 198504, St. Petersburg, Russia.,Spin Optics Laboratory, St. Petersburg State University, 198504, St. Petersburg, Russia
| | - F Heisterkamp
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany.,Federal Institute for Occupational Safety and Health (BAuA), 44149, Dortmund, Germany
| | - I A Yugova
- Physical Faculty of St. Petersburg State University, 198504, St. Petersburg, Russia
| | - V L Korenev
- Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - D R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany.,Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - A Pawlis
- Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - M Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany.,Ioffe Institute, Russian Academy of Sciences, 194021, St. Petersburg, Russia
| | - A Greilich
- Experimentelle Physik 2, Technische Universität Dortmund, 44221, Dortmund, Germany.
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11
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Heo J, Hong CH, Kang MS, Yang H, Yang HJ, Hong JP, Choi SG. Implementation of controlled quantum teleportation with an arbitrator for secure quantum channels via quantum dots inside optical cavities. Sci Rep 2017; 7:14905. [PMID: 29097727 PMCID: PMC5668345 DOI: 10.1038/s41598-017-14515-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 09/29/2017] [Indexed: 11/09/2022] Open
Abstract
We propose a controlled quantum teleportation scheme to teleport an unknown state based on the interactions between flying photons and quantum dots (QDs) confined within single- and double-sided cavities. In our scheme, users (Alice and Bob) can teleport the unknown state through a secure entanglement channel under the control and distribution of an arbitrator (Trent). For construction of the entanglement channel, Trent utilizes the interactions between two photons and the QD-cavity system, which consists of a charged QD (negatively charged exciton) inside a single-sided cavity. Subsequently, Alice can teleport the unknown state of the electron spin in a QD inside a double-sided cavity to Bob's electron spin in a QD inside a single-sided cavity assisted by the channel information from Trent. Furthermore, our scheme using QD-cavity systems is feasible with high fidelity, and can be experimentally realized with current technologies.
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Affiliation(s)
- Jino Heo
- College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea
| | - Chang-Ho Hong
- National Security Research Institute, P.O. Box 1, Yuseong, Daejeon, 34188, Republic of Korea
| | - Min-Sung Kang
- Center for Quantum Information, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea
| | - Hyeon Yang
- College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea
| | - Hyung-Jin Yang
- Department of Physics, Korea University, Sejong, 339-700, Republic of Korea
| | - Jong-Phil Hong
- College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea
| | - Seong-Gon Choi
- College of Electrical and Computer Engineering, Chungbuk National University, Chungdae-ro 1, Seowon-Gu, Cheongju, Republic of Korea.
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12
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Éthier-Majcher G, Gangloff D, Stockill R, Clarke E, Hugues M, Le Gall C, Atatüre M. Improving a Solid-State Qubit through an Engineered Mesoscopic Environment. PHYSICAL REVIEW LETTERS 2017; 119:130503. [PMID: 29341723 DOI: 10.1103/physrevlett.119.130503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 06/07/2023]
Abstract
A controlled quantum system can alter its environment by feedback, leading to reduced-entropy states of the environment and to improved system coherence. Here, using a quantum-dot electron spin as a control and probe, we prepare the quantum-dot nuclei under the feedback of coherent population trapping and observe their evolution from a thermal to a reduced-entropy state, with the immediate consequence of extended qubit coherence. Via Ramsey interferometry on the electron spin, we directly access the nuclear distribution following its preparation and measure the emergence and decay of correlations within the nuclear ensemble. Under optimal feedback, the inhomogeneous dephasing time of the electron, T_{2}^{*}, is extended by an order of magnitude to 39 ns. Our results can be readily exploited in quantum information protocols utilizing spin-photon entanglement and represent a step towards creating quantum many-body states in a mesoscopic nuclear-spin ensemble.
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Affiliation(s)
- G Éthier-Majcher
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - D Gangloff
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - R Stockill
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - E Clarke
- EPSRC National Centre for III-V Technologies, University of Sheffield, Sheffield S1 3JD, United Kingdom
| | - M Hugues
- Université Côte d'Azur, CNRS, CRHEA, rue Bernard Gregory, 06560 Valbonne, France
| | - C Le Gall
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - M Atatüre
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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13
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Gustavsson S, Yan F, Catelani G, Bylander J, Kamal A, Birenbaum J, Hover D, Rosenberg D, Samach G, Sears AP, Weber SJ, Yoder JL, Clarke J, Kerman AJ, Yoshihara F, Nakamura Y, Orlando TP, Oliver WD. Suppressing relaxation in superconducting qubits by quasiparticle pumping. Science 2016; 354:1573-1577. [PMID: 27940578 DOI: 10.1126/science.aah5844] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/21/2016] [Indexed: 11/02/2022]
Abstract
Dynamical error suppression techniques are commonly used to improve coherence in quantum systems. They reduce dephasing errors by applying control pulses designed to reverse erroneous coherent evolution driven by environmental noise. However, such methods cannot correct for irreversible processes such as energy relaxation. We investigate a complementary, stochastic approach to reducing errors: Instead of deterministically reversing the unwanted qubit evolution, we use control pulses to shape the noise environment dynamically. In the context of superconducting qubits, we implement a pumping sequence to reduce the number of unpaired electrons (quasiparticles) in close proximity to the device. A 70% reduction in the quasiparticle density results in a threefold enhancement in qubit relaxation times and a comparable reduction in coherence variability.
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Affiliation(s)
- Simon Gustavsson
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Fei Yan
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Gianluigi Catelani
- Forschungszentrum Jülich, Peter Grünberg Institut (PGI-2), 52425 Jülich, Germany
| | - Jonas Bylander
- Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
| | - Archana Kamal
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jeffrey Birenbaum
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - David Hover
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Danna Rosenberg
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Gabriel Samach
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Adam P Sears
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Steven J Weber
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Jonilyn L Yoder
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - John Clarke
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Andrew J Kerman
- Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA
| | - Fumiki Yoshihara
- The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan
| | - Yasunobu Nakamura
- Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198, Japan.,Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Terry P Orlando
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - William D Oliver
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Massachusetts Institute of Technology (MIT) Lincoln Laboratory, 244 Wood Street, Lexington, MA 02420, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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14
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Wüst G, Munsch M, Maier F, Kuhlmann AV, Ludwig A, Wieck AD, Loss D, Poggio M, Warburton RJ. Role of the electron spin in determining the coherence of the nuclear spins in a quantum dot. NATURE NANOTECHNOLOGY 2016; 11:885-889. [PMID: 27428274 DOI: 10.1038/nnano.2016.114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 05/23/2016] [Indexed: 06/06/2023]
Abstract
A huge effort is underway to develop semiconductor nanostructures as low-noise qubits. A key source of dephasing for an electron spin qubit in GaAs and in naturally occurring Si is the nuclear spin bath. The electron spin is coupled to each nuclear spin by the hyperfine interaction. The same interaction also couples two remote nuclear spins via a common coupling to the delocalized electron. It has been suggested that this interaction limits both electron and nuclear spin coherence, but experimental proof is lacking. We show that the nuclear spin decoherence time decreases by two orders of magnitude on occupying an empty quantum dot with a single electron, recovering to its original value for two electrons. In the case of one electron, agreement with a model calculation verifies the hypothesis of an electron-mediated nuclear spin-nuclear spin coupling. The results establish a framework to understand the main features of this complex interaction in semiconductor nanostructures.
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Affiliation(s)
- Gunter Wüst
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Mathieu Munsch
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Franziska Maier
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Andreas V Kuhlmann
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Daniel Loss
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Martino Poggio
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Richard J Warburton
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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15
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Luo MX, Deng Y, Li HR, Ma SY. Photonic ququart logic assisted by the cavity-QED system. Sci Rep 2015; 5:13255. [PMID: 26272869 PMCID: PMC4536487 DOI: 10.1038/srep13255] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 07/23/2015] [Indexed: 11/23/2022] Open
Abstract
Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions of qubit systems, we investigate the possibility of ququart systems (four-dimensional states) dependent on two DOFs of photon systems. We propose some useful one-parameter four-dimensional quantum transformations for the construction of universal ququart logic gates. The interface between the spin of a photon and an electron spin confined in a quantum dot embedded in a microcavity is applied to build universal ququart logic gates on the photon system with two freedoms. Our elementary controlled-ququart gates cost no more than 8 CNOT gates in a qubit system, which is far less than the 104 CNOT gates required for a general four-qubit logic gate. The ququart logic is also used to generate useful hyperentanglements and hyperentanglement-assisted quantum error-correcting code, which may be available in modern physical technology.
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Affiliation(s)
- Ming-Xing Luo
- Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China
| | - Yun Deng
- School of Computer Science, Sichuan University of Science & Engineering, Zigong 64300, China
| | - Hui-Ran Li
- Information Security and National Computing Grid Laboratory, Southwest Jiaotong University, Chengdu 610031, China
| | - Song-Ya Ma
- School of Mathematics and Statistics, Henan University, Kaifeng 475004, China
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16
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Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain. Nat Commun 2015; 6:6348. [PMID: 25704639 PMCID: PMC4346613 DOI: 10.1038/ncomms7348] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 01/20/2015] [Indexed: 11/08/2022] Open
Abstract
Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear-nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2-4.5 ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging.
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17
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Yoneda J, Otsuka T, Nakajima T, Takakura T, Obata T, Pioro-Ladrière M, Lu H, Palmstrøm CJ, Gossard AC, Tarucha S. Fast electrical control of single electron spins in quantum dots with vanishing influence from nuclear spins. PHYSICAL REVIEW LETTERS 2014; 113:267601. [PMID: 25615383 DOI: 10.1103/physrevlett.113.267601] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Indexed: 06/04/2023]
Abstract
We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96%, a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots.
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Affiliation(s)
- J Yoneda
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and RIKEN, Center for Emergent Matter Science, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
| | - T Otsuka
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and RIKEN, Center for Emergent Matter Science, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
| | - T Nakajima
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and RIKEN, Center for Emergent Matter Science, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
| | - T Takakura
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - T Obata
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - M Pioro-Ladrière
- Département de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada and CIFAR Program in Quantum Information Science, Canadian Institute for Advanced Research (CIFAR), Toronto, Ontario M5G 1Z8, Canada
| | - H Lu
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - C J Palmstrøm
- Materials Department, University of California, Santa Barbara, California 93106, USA and Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA
| | - A C Gossard
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - S Tarucha
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan and RIKEN, Center for Emergent Matter Science, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
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18
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Liu GQ, Jiang QQ, Chang YC, Liu DQ, Li WX, Gu CZ, Po HC, Zhang WX, Zhao N, Pan XY. Protection of centre spin coherence by dynamic nuclear spin polarization in diamond. NANOSCALE 2014; 6:10134-10139. [PMID: 25042514 DOI: 10.1039/c4nr02007c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We experimentally investigate the protection of electron spin coherence of a nitrogen-vacancy (NV) centre in diamond by dynamic nuclear spin polarization (DNP). The electron spin decoherence of an NV centre is caused by the magnetic field fluctuation of the (13)C nuclear spin bath, which contributes large thermal fluctuation to the centre electron spin when it is in an equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under the Hartmann-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time (T). Optimal conditions for the DNP process, including the pumping pulse duration and repeat numbers, are proposed by numerical simulation and confirmed by experiment. We also studied the depolarization effect of laser pulses. Our results provide a new route for quantum information processing and quantum simulation using the polarized nuclear spin bath.
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Affiliation(s)
- Gang-Qin Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
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19
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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: 130] [Impact Index Per Article: 13.0] [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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20
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Nguyen KT, Lilly MP, Nielsen E, Bishop N, Rahman R, Young R, Wendt J, Dominguez J, Pluym T, Stevens J, Lu TM, Muller R, Carroll MS. Charge sensed Pauli blockade in a metal-oxide-semiconductor lateral double quantum dot. NANO LETTERS 2013; 13:5785-5790. [PMID: 24199677 DOI: 10.1021/nl4020759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report Pauli blockade in a multielectron silicon metal-oxide-semiconductor double quantum dot with an integrated charge sensor. The current is rectified up to a blockade energy of 0.18 ± 0.03 meV. The blockade energy is analogous to singlet-triplet splitting in a two electron double quantum dot. Built-in imbalances of tunnel rates in the MOS DQD obfuscate some edges of the bias triangles. A method to extract the bias triangles is described, and a numeric rate-equation simulation is used to understand the effect of tunneling imbalances and finite temperature on charge stability (honeycomb) diagram, in particular the identification of missing and shifting edges. A bound on relaxation time of the triplet-like state is also obtained from this measurement.
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Affiliation(s)
- Khoi T Nguyen
- Sandia National Laboratories , Albuquerque, New Mexico 87185, United States
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21
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Danon J, Wang X, Manchon A. Pauli spin blockade and the ultrasmall magnetic field effect. PHYSICAL REVIEW LETTERS 2013; 111:066802. [PMID: 23971599 DOI: 10.1103/physrevlett.111.066802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Indexed: 06/02/2023]
Abstract
Based on the spin-blockade model for organic magnetoresistance, we present an analytic expression for the polaron-bipolaron transition rate, taking into account the effective nuclear fields on the two sites. We reveal the physics behind the qualitatively different magnetoconductance line shapes observed in experiment, as well as the ultrasmall magnetic field effect (USFE). Since our findings agree in detail with recent experiments, they also indirectly provide support for the spin-blockade interpretation of organic magnetoresistance. In addition, we predict the existence of a similar USFE in semiconductor double quantum dots tuned to the spin-blockade regime.
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Affiliation(s)
- Jeroen Danon
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100 Copenhagen, Denmark
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22
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Chekhovich EA, Makhonin MN, Tartakovskii AI, Yacoby A, Bluhm H, Nowack KC, Vandersypen LMK. Nuclear spin effects in semiconductor quantum dots. NATURE MATERIALS 2013; 12:494-504. [PMID: 23695746 DOI: 10.1038/nmat3652] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 04/12/2013] [Indexed: 06/02/2023]
Abstract
The interaction of an electronic spin with its nuclear environment, an issue known as the central spin problem, has been the subject of considerable attention due to its relevance for spin-based quantum computation using semiconductor quantum dots. Independent control of the nuclear spin bath using nuclear magnetic resonance techniques and dynamic nuclear polarization using the central spin itself offer unique possibilities for manipulating the nuclear bath with significant consequences for the coherence and controlled manipulation of the central spin. Here we review some of the recent optical and transport experiments that have explored this central spin problem using semiconductor quantum dots. We focus on the interaction between 10(4)-10(6) nuclear spins and a spin of a single electron or valence-band hole. We also review the experimental techniques as well as the key theoretical ideas and the implications for quantum information science.
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Affiliation(s)
- E A Chekhovich
- Department of Physics and Astronomy, University of Sheffield, Sheffield, UK
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23
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Petersen G, Hoffmann EA, Schuh D, Wegscheider W, Giedke G, Ludwig S. Large nuclear spin polarization in gate-defined quantum dots using a single-domain nanomagnet. PHYSICAL REVIEW LETTERS 2013; 110:177602. [PMID: 23679779 DOI: 10.1103/physrevlett.110.177602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 03/13/2013] [Indexed: 06/02/2023]
Abstract
The electron-nuclei (hyperfine) interaction is central to spin qubits in solid state systems. It can be a severe decoherence source but also allows dynamic access to the nuclear spin states. We study a double quantum dot exposed to an on-chip single-domain nanomagnet and show that its inhomogeneous magnetic field crucially modifies the complex nuclear spin dynamics such that the Overhauser field tends to compensate external magnetic fields. This turns out to be beneficial for polarizing the nuclear spin ensemble. We reach a nuclear spin polarization of ≃50%, unrivaled in lateral dots, and explain our manipulation technique using a comprehensive rate equation model.
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Affiliation(s)
- Gunnar Petersen
- Center for Nanoscience and Fakultät für Physik, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany
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24
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Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor. Nat Commun 2013; 4:1751. [PMID: 23612292 DOI: 10.1038/ncomms2776] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/21/2013] [Indexed: 11/08/2022] Open
Abstract
Nuclear spin hyperpolarization is essential to future solid-state quantum computation using nuclear spin qubits and in highly sensitive magnetic resonance imaging. Though efficient dynamic nuclear polarization in semiconductors has been demonstrated at low temperatures for decades, its realization at room temperature is largely lacking. Here we demonstrate that a combined effect of efficient spin-dependent recombination and hyperfine coupling can facilitate strong dynamic nuclear polarization of a defect atom in a semiconductor at room temperature. We provide direct evidence that a sizeable nuclear field (~150 Gauss) and nuclear spin polarization (~15%) sensed by conduction electrons in GaNAs originates from dynamic nuclear polarization of a Ga interstitial defect. We further show that the dynamic nuclear polarization process is remarkably fast and is completed in <5 μs at room temperature. The proposed new concept could pave a way to overcome a major obstacle in achieving strong dynamic nuclear polarization at room temperature, desirable for practical device applications.
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25
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Faribault A, Schuricht D. Integrability-based analysis of the hyperfine-interaction-induced decoherence in quantum dots. PHYSICAL REVIEW LETTERS 2013; 110:040405. [PMID: 25166143 DOI: 10.1103/physrevlett.110.040405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Indexed: 06/03/2023]
Abstract
Using the algebraic Bethe ansatz in conjunction with a simple Monte Carlo sampling technique, we study the problem of the decoherence of a central spin coupled to a nuclear spin bath. We describe in detail the full crossover from strong to weak external magnetic field, a limit where a large nondecaying coherence factor is found. This feature is explained by Bose-Einstein-condensate-like physics which also allows us to argue that the corresponding zero frequency peak would not be broadened by statistical or ensemble averaging.
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Affiliation(s)
- Alexandre Faribault
- Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany
| | - Dirk Schuricht
- Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany
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26
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Li Y, Aolita L, Chang DE, Kwek LC. Robust-fidelity atom-photon entangling gates in the weak-coupling regime. PHYSICAL REVIEW LETTERS 2012; 109:160504. [PMID: 23215063 DOI: 10.1103/physrevlett.109.160504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Indexed: 06/01/2023]
Abstract
We describe a simple entangling principle based on the scattering of photons off single emitters in one-dimensional waveguides (or extremely lossy cavities). The scheme can be applied to polarization- or time bin-encoded photonic qubits, and features a filtering mechanism that works effectively as a built-in error-correction directive. This automatically maps imperfections from the dominant sources of errors into heralded losses instead of infidelities, something highly advantageous, for instance, in quantum information applications. The scheme is thus adequate for high-fidelity maximally entangling gates even in the weak-coupling regime. These, in turn, can be directly used to store and retrieve photonic-qubit states, thereby completing an atom-photon interface toolbox, or applied to sequential measurement-based quantum computations with atomic memories.
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Affiliation(s)
- Ying Li
- Centre for Quantum Technologies, National University of Singapore, Singapore 117543, Singapore
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27
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Raith M, Stano P, Baruffa F, Fabian J. Theory of spin relaxation in two-electron lateral coupled quantum dots. PHYSICAL REVIEW LETTERS 2012; 108:246602. [PMID: 23004302 DOI: 10.1103/physrevlett.108.246602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Indexed: 06/01/2023]
Abstract
A global quantitative picture of the phonon-induced two-electron spin relaxation in GaAs double quantum dots is presented using highly accurate numerics. Wide regimes of interdot coupling, magnetic field magnitude and orientation, and detuning are explored in the presence of a nuclear bath. Most important, the giant magnetic anisotropy of the singlet-triplet relaxation can be controlled by detuning switching the principal anisotropy axes: a protected state becomes unprotected upon detuning and vice versa. It is also established that nuclear spins can dominate spin relaxation for unpolarized triplets even at high magnetic fields, contrary to common belief.
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Affiliation(s)
- Martin Raith
- Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany
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28
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29
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Maune BM, Borselli MG, Huang B, Ladd TD, Deelman PW, Holabird KS, Kiselev AA, Alvarado-Rodriguez I, Ross RS, Schmitz AE, Sokolich M, Watson CA, Gyure MF, Hunter AT. Coherent singlet-triplet oscillations in a silicon-based double quantum dot. Nature 2012; 481:344-7. [PMID: 22258613 DOI: 10.1038/nature10707] [Citation(s) in RCA: 414] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 11/01/2011] [Indexed: 11/09/2022]
Abstract
Silicon is more than the dominant material in the conventional microelectronics industry: it also has potential as a host material for emerging quantum information technologies. Standard fabrication techniques already allow the isolation of single electron spins in silicon transistor-like devices. Although this is also possible in other materials, silicon-based systems have the advantage of interacting more weakly with nuclear spins. Reducing such interactions is important for the control of spin quantum bits because nuclear fluctuations limit quantum phase coherence, as seen in recent experiments in GaAs-based quantum dots. Advances in reducing nuclear decoherence effects by means of complex control still result in coherence times much shorter than those seen in experiments on large ensembles of impurity-bound electrons in bulk silicon crystals. Here we report coherent control of electron spins in two coupled quantum dots in an undoped Si/SiGe heterostructure and show that this system has a nuclei-induced dephasing time of 360 nanoseconds, which is an increase by nearly two orders of magnitude over similar measurements in GaAs-based quantum dots. The degree of phase coherence observed, combined with fast, gated electrical initialization, read-out and control, should motivate future development of silicon-based quantum information processors.
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Affiliation(s)
- B M Maune
- HRL Laboratories LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA.
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30
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Kobayashi T, Hitachi K, Sasaki S, Muraki K. Observation of hysteretic transport due to dynamic nuclear spin polarization in a GaAs lateral double quantum dot. PHYSICAL REVIEW LETTERS 2011; 107:216802. [PMID: 22181907 DOI: 10.1103/physrevlett.107.216802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Indexed: 05/31/2023]
Abstract
We report a new transport feature in a GaAs lateral double quantum dot that emerges for magnetic-field sweeps and shows hysteresis due to dynamic nuclear spin polarization (DNP). This DNP signal appears in the Coulomb blockade regime by virtue of the finite interdot tunnel coupling and originates from the crossing between ground levels of the spin triplet and singlet extensively used for nuclear spin manipulations in pulsed-gate experiments. The magnetic-field dependence of the current level is suggestive of unbalanced DNP between the two dots, which opens up the possibility of controlling electron and nuclear spin states via dc transport.
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Affiliation(s)
- Takashi Kobayashi
- NTT Basic Research Laboratories, NTT Corporation, Morinosato-Wakamiya, Atsugi, Japan
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31
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Latta C, Srivastava A, Imamoğlu A. Hyperfine interaction-dominated dynamics of nuclear spins in self-assembled InGaAs quantum dots. PHYSICAL REVIEW LETTERS 2011; 107:167401. [PMID: 22107424 DOI: 10.1103/physrevlett.107.167401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Indexed: 05/25/2023]
Abstract
We measure the dynamics of nuclear spins in a single-electron charged self-assembled InGaAs quantum dot with negligible nuclear spin diffusion due to dipole-dipole interaction and identify two distinct mechanisms responsible for the decay of the Overhauser field. We attribute a temperature-independent decay lasting ∼100 sec at 5 T to intradot diffusion induced by hyperfine-mediated indirect nuclear spin interaction. By repeated polarization of the nuclear spins, this diffusion induced partial decay can be suppressed. We also observe a gate voltage and temperature-dependent decay stemming from cotunneling mediated nuclear spin flips that can be prolonged to ∼30 h by adjusting the gate voltage and lowering the temperature to ∼200 mK. Our measurements indicate possibilities for exploring quantum dynamics of the central spin model.
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Affiliation(s)
- Christian Latta
- Institute of Quantum Electronics, ETH-Zürich, Zürich, Switzerland.
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32
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Mariantoni M, Wang H, Yamamoto T, Neeley M, Bialczak RC, Chen Y, Lenander M, Lucero E, O’Connell AD, Sank D, Weides M, Wenner J, Yin Y, Zhao J, Korotkov AN, Cleland AN, Martinis JM. Implementing the Quantum von Neumann Architecture with Superconducting Circuits. Science 2011; 334:61-5. [DOI: 10.1126/science.1208517] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Matteo Mariantoni
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106–9530, USA
| | - H. Wang
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - T. Yamamoto
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
- Green Innovation Research Laboratories, NEC Corporation, Tsukuba, Ibaraki 305-8501, Japan
| | - M. Neeley
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - Radoslaw C. Bialczak
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - Y. Chen
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - M. Lenander
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - Erik Lucero
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - A. D. O’Connell
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - D. Sank
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - M. Weides
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - J. Wenner
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - Y. Yin
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - J. Zhao
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
| | - A. N. Korotkov
- Department of Electrical Engineering, University of California, Riverside, CA 92521, USA
| | - A. N. Cleland
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106–9530, USA
| | - John M. Martinis
- Department of Physics, University of California, Santa Barbara, CA 93106–9530, USA
- California NanoSystems Institute, University of California, Santa Barbara, CA 93106–9530, USA
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33
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Barnes E, Economou SE. Electron-nuclear dynamics in a quantum dot under nonunitary electron control. PHYSICAL REVIEW LETTERS 2011; 107:047601. [PMID: 21867043 DOI: 10.1103/physrevlett.107.047601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2011] [Indexed: 05/31/2023]
Abstract
We introduce a method for solving the problem of an externally controlled electron spin in a quantum dot interacting with host nuclei via the hyperfine interaction. Our method accounts for generalized (nonunitary) evolution effected by external controls and the environment, such as coherent lasers combined with spontaneous emission. As a concrete example, we develop the microscopic theory of the dynamics of nuclear-induced frequency focusing as first measured in Science 317, 1896 (2007); we find that the nuclear relaxation rates are several orders of magnitude faster than those quoted in that work.
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Affiliation(s)
- Edwin Barnes
- Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
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34
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Takahashi R, Kono K, Tarucha S, Ono K. Voltage-selective bidirectional polarization and coherent rotation of nuclear spins in quantum dots. PHYSICAL REVIEW LETTERS 2011; 107:026602. [PMID: 21797631 DOI: 10.1103/physrevlett.107.026602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Indexed: 05/31/2023]
Abstract
We propose and demonstrate that the nuclear spins of the host lattice in GaAs double quantum dots can be polarized in either of two opposite directions, parallel or antiparallel to an external magnetic field. The direction is selected by adjusting the dc voltage. This nuclear polarization manifests itself by repeated controlled electron-nuclear spin scattering in the Pauli spin-blockade state. Polarized nuclei are also controlled by means of nuclear magnetic resonance. This Letter confirms that the nuclear spins in quantum dots are long-lived quantum states with a coherence time of up to 1 ms, and may be a promising resource for quantum-information processing such as quantum memories for electron spin qubits.
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Affiliation(s)
- R Takahashi
- Low Temperature Physics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan
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35
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Steinigeweg R, Langer S, Heidrich-Meisner F, McCulloch IP, Brenig W. Coherent spin-current oscillations in transverse magnetic fields. PHYSICAL REVIEW LETTERS 2011; 106:160602. [PMID: 21599345 DOI: 10.1103/physrevlett.106.160602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 03/25/2011] [Indexed: 05/30/2023]
Abstract
We address the coherence of the dynamics of spin-currents with components transverse to an external magnetic field for the spin-1/2 Heisenberg chain. We study current autocorrelations at finite temperatures and the real-time dynamics of currents at zero temperature. Besides a coherent Larmor oscillation, we find an additional collective oscillation at higher frequencies, emerging as a coherent many-magnon effect at low temperatures. Using numerical and analytical methods, we analyze the oscillation frequency and decay time of this coherent current-mode versus temperature and magnetic field.
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Affiliation(s)
- Robin Steinigeweg
- Institute for Theoretical Physics, Technical University Braunschweig, Braunschweig, Germany.
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36
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Liew TCH, Savona V. Optically erasing disorder in semiconductor microcavities with dynamic nuclear polarization. PHYSICAL REVIEW LETTERS 2011; 106:146404. [PMID: 21561208 DOI: 10.1103/physrevlett.106.146404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 03/11/2011] [Indexed: 05/30/2023]
Abstract
The mean squared value of the photonic disorder is found to be reduced by a factor of 100 in a typical GaAs based microcavity when exposed to a circularly polarized continuous wave optical pump without any special spatial patterning. Resonant excitation of the cavity mode excites a spatially nonuniform distribution of spin-polarized electrons, which depends on the photonic disorder profile. Electrons transfer spin to nuclei via the hyperfine contact interaction, inducing a long-living Overhauser magnetic field able to modify the potential of exciton polaritons.
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Affiliation(s)
- T C H Liew
- Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne EPFL, CH-1015 Lausanne, Switzerland
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37
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Issler M, Kessler EM, Giedke G, Yelin S, Cirac I, Lukin MD, Imamoglu A. Nuclear spin cooling using Overhauser-field selective coherent population trapping. PHYSICAL REVIEW LETTERS 2010; 105:267202. [PMID: 21231709 DOI: 10.1103/physrevlett.105.267202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2010] [Revised: 11/17/2010] [Indexed: 05/25/2023]
Abstract
We show that a quantum interference effect in optical absorption from two electronic spin states of a solid-state emitter can be used to prepare the surrounding environment of nuclear spins in well-defined states, thereby suppressing electronic spin dephasing. The coupled electron-nuclei system evolves into a coherent population trapping state by optical-excitation-induced nuclear-spin diffusion for a broad range of initial optical detunings. The spectroscopic signature of this evolution where the single-electron strongly modifies its environment is a drastic broadening of the dark resonance in optical absorption experiments. The large difference in electronic and nuclear time scales allows us to verify the preparation of nuclear spins in the desired state.
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Affiliation(s)
- M Issler
- Institute of Quantum Electronics, ETH-Zürich, Zürich, Switzerland
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38
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Fischer J, Loss D. Hybridization and spin decoherence in heavy-hole quantum dots. PHYSICAL REVIEW LETTERS 2010; 105:266603. [PMID: 21231694 DOI: 10.1103/physrevlett.105.266603] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Indexed: 05/30/2023]
Abstract
We theoretically investigate the spin dynamics of a heavy hole confined to an unstrained III-V semiconductor quantum dot and interacting with a narrowed nuclear-spin bath. We show that band hybridization leads to an exponential decay of hole-spin superpositions due to hyperfine-mediated nuclear pair flips, and that the accordant single-hole-spin decoherence time T2 can be tuned over many orders of magnitude by changing external parameters. In particular, we show that, under experimentally accessible conditions, it is possible to suppress hyperfine-mediated nuclear-pair-flip processes so strongly that hole-spin quantum dots may be operated beyond the "ultimate limitation" set by the hyperfine interaction which is present in other spin-qubit candidate systems.
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Affiliation(s)
- Jan Fischer
- Department of Physics, University of Basel, Basel, Switzerland
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39
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Nadj-Perge S, Frolov SM, Bakkers EPAM, Kouwenhoven LP. Spin–orbit qubit in a semiconductor nanowire. Nature 2010; 468:1084-7. [DOI: 10.1038/nature09682] [Citation(s) in RCA: 532] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 11/10/2010] [Indexed: 11/09/2022]
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40
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Bluhm H, Foletti S, Mahalu D, Umansky V, Yacoby A. Enhancing the coherence of a spin qubit by operating it as a feedback loop that controls its nuclear spin bath. PHYSICAL REVIEW LETTERS 2010; 105:216803. [PMID: 21231340 DOI: 10.1103/physrevlett.105.216803] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2010] [Indexed: 05/30/2023]
Abstract
In many realizations of electron spin qubits the dominant source of decoherence is the fluctuating nuclear spin bath of the host material. The slowness of this bath lends itself to a promising mitigation strategy where the nuclear spin bath is prepared in a narrowed state with suppressed fluctuations. Here, this approach is realized for a two-electron spin qubit in a GaAs double quantum dot and a nearly tenfold increase in the inhomogeneous dephasing time T₂* is demonstrated. Between subsequent measurements, the bath is prepared by using the qubit as a feedback loop that first measures its nuclear environment by coherent precession, and then polarizes it depending on the final state. This procedure results in a stable fixed point at a nonzero polarization gradient between the two dots, which enables fast universal qubit control.
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Affiliation(s)
- Hendrik Bluhm
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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41
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Ladd TD, Press D, De Greve K, McMahon PL, Friess B, Schneider C, Kamp M, Höfling S, Forchel A, Yamamoto Y. Pulsed nuclear pumping and spin diffusion in a single charged quantum dot. PHYSICAL REVIEW LETTERS 2010; 105:107401. [PMID: 20867546 DOI: 10.1103/physrevlett.105.107401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Indexed: 05/29/2023]
Abstract
We report the observation of a feedback process between the nuclear spins in a single charged quantum dot under coherently pulsed optical excitation and its trion transition. The optical pulse sequence intersperses resonant narrow-band pumping for spin initialization with off-resonant ultrafast pulses for coherent electron-spin rotation. A hysteretic sawtooth pattern in the free-induction decay of the single electron spin is observed; a mathematical model indicates a competition between optical nuclear pumping and nuclear spin-diffusion. This effect allows dynamic tuning of the electron Larmor frequency to a value determined by the pulse timing, potentially allowing more complex coherent control operations.
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Affiliation(s)
- Thaddeus D Ladd
- E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
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42
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Reilly DJ, Taylor JM, Petta JR, Marcus CM, Hanson MP, Gossard AC. Exchange control of nuclear spin diffusion in a double quantum dot. PHYSICAL REVIEW LETTERS 2010; 104:236802. [PMID: 20867261 DOI: 10.1103/physrevlett.104.236802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Indexed: 05/25/2023]
Abstract
The influence of gate-controlled two-electron exchange on the relaxation of nuclear polarization in small ensembles (N∼10(6)) of nuclear spins is examined in a GaAs double quantum dot system. Waiting in the (2,0) charge configuration, which has large exchange splitting, reduces the nuclear diffusion rate compared to that of the (1,1) configuration. Matching exchange to Zeeman splitting significantly increases the nuclear diffusion rate.
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Affiliation(s)
- D J Reilly
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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43
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Gullans M, Krich JJ, Taylor JM, Bluhm H, Halperin BI, Marcus CM, Stopa M, Yacoby A, Lukin MD. Dynamic nuclear polarization in double quantum dots. PHYSICAL REVIEW LETTERS 2010; 104:226807. [PMID: 20867197 DOI: 10.1103/physrevlett.104.226807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Indexed: 05/29/2023]
Abstract
We theoretically investigate the controlled dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. Three regimes of long-term dynamics are identified, including the buildup of a large difference in the Overhauser fields across the dots, the saturation of the nuclear polarization process associated with formation of so-called "dark states", and the elimination of the difference field. We show that in the case of unequal dots, buildup of difference fields generally accompanies the nuclear polarization process, whereas for nearly identical dots, buildup of difference fields competes with polarization saturation in dark states. The elimination of the difference field does not, in general, correspond to a stable steady state of the polarization process.
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Affiliation(s)
- M Gullans
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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44
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Bonato C, Haupt F, Oemrawsingh SSR, Gudat J, Ding D, van Exter MP, Bouwmeester D. CNOT and Bell-state analysis in the weak-coupling cavity QED regime. PHYSICAL REVIEW LETTERS 2010; 104:160503. [PMID: 20482035 DOI: 10.1103/physrevlett.104.160503] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Indexed: 05/29/2023]
Abstract
We propose an interface between the spin of a photon and the spin of an electron confined in a quantum dot embedded in a microcavity operating in the weak-coupling regime. This interface, based on spin selective photon reflection from the cavity, can be used to construct a CNOT gate, a multiphoton entangler and a photonic Bell-state analyzer. Finally, we analyze experimental feasibility, concluding that the schemes can be implemented with current technology.
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Affiliation(s)
- Cristian Bonato
- Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands
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45
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Chekhovich EA, Makhonin MN, Kavokin KV, Krysa AB, Skolnick MS, Tartakovskii AI. Pumping of nuclear spins by optical excitation of spin-forbidden transitions in a quantum dot. PHYSICAL REVIEW LETTERS 2010; 104:066804. [PMID: 20366847 DOI: 10.1103/physrevlett.104.066804] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Indexed: 05/29/2023]
Abstract
We demonstrate that efficient optical pumping of nuclear spins in semiconductor quantum dots (QDs) can be achieved by resonant pumping of optically forbidden transitions. This process corresponds to one-to-one conversion of a photon absorbed by the dot into a polarized nuclear spin, and also has potential for initialization of hole spin in QDs. We find that by employing this spin-forbidden process, nuclear polarization of 65% can be achieved, markedly higher than from pumping the allowed transition, which saturates due to the low probability of electron-nuclear spin flip-flop.
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Affiliation(s)
- E A Chekhovich
- Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
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46
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Affiliation(s)
- Guido Burkard
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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47
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McCamey DR, van Schooten KJ, Baker WJ, Lee SY, Paik SY, Lupton JM, Boehme C. Hyperfine-field-mediated spin beating in electrostatically bound charge carrier pairs. PHYSICAL REVIEW LETTERS 2010; 104:017601. [PMID: 20366393 DOI: 10.1103/physrevlett.104.017601] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Indexed: 05/29/2023]
Abstract
Organic semiconductors offer a unique environment to probe the hyperfine coupling of electronic spins to a nuclear spin bath. We explore the interaction of spins in electron-hole pairs in the presence of inhomogeneous hyperfine fields by monitoring the modulation of the current through an organic light emitting diode under coherent spin-resonant excitation. At weak driving fields, only one of the two spins in the pair precesses. As the driving field exceeds the difference in local hyperfine field experienced by electron and hole, both spins precess, leading to pronounced spin beating in the transient Rabi flopping of the current. We use this effect to measure the magnitude and spatial variation in hyperfine field on the scale of single carrier pairs, as required for evaluating models of organic magnetoresistance, improving organic spintronics devices, and illuminating spin decoherence mechanisms.
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Affiliation(s)
- D R McCamey
- Department of Physics and Astronomy, University of Utah, 115 South 1400 East, Salt Lake City, Utah 84112, USA
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48
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Barthel C, Reilly DJ, Marcus CM, Hanson MP, Gossard AC. Rapid single-shot measurement of a singlet-triplet qubit. PHYSICAL REVIEW LETTERS 2009; 103:160503. [PMID: 19905680 DOI: 10.1103/physrevlett.103.160503] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Indexed: 05/28/2023]
Abstract
We report repeated single-shot measurements of the two-electron spin state in a GaAs double quantum dot. The readout allows measurement with a fidelity above 90% with a approximately 7 micros cycle time. Hyperfine-induced precession between singlet and triplet states of the two-electron system are directly observed, as nuclear Overhauser fields are quasistatic on the time scale of the measurement cycle. Repeated measurements on millisecond to second time scales reveal the evolution of the nuclear environment.
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Affiliation(s)
- C Barthel
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
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49
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Simmons CB, Thalakulam M, Rosemeyer BM, Van Bael BJ, Sackmann EK, Savage DE, Lagally MG, Joynt R, Friesen M, Coppersmith SN, Eriksson MA. Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot. NANO LETTERS 2009; 9:3234-3238. [PMID: 19645459 DOI: 10.1021/nl9014974] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report integrated charge sensing measurements on a Si/SiGe double quantum dot. The quantum dot is shown to be tunable from a single, large dot to a well-isolated double dot. Charge sensing measurements enable the extraction of the tunnel coupling t between the quantum dots as a function of the voltage on the top gates defining the device. Control of the voltage on a single such gate tunes the barrier separating the two dots. The measured tunnel coupling is an exponential function of the gate voltage. The ability to control t is an important step toward controlling spin qubits in silicon quantum dots.
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Affiliation(s)
- C B Simmons
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
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50
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Danon J, Vink IT, Koppens FHL, Nowack KC, Vandersypen LMK, Nazarov YV. Multiple nuclear polarization States in a double quantum dot. PHYSICAL REVIEW LETTERS 2009; 103:046601. [PMID: 19659378 DOI: 10.1103/physrevlett.103.046601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Indexed: 05/28/2023]
Abstract
We observe multiple stable states of nuclear polarization and nuclear self-tuning over a large range of fields in a double quantum dot under conditions of electron spin resonance. The observations can be understood within an elaborated theoretical rate equation model for the polarization in each of the dots, in the limit of strong driving. This model also captures unusual features of the data, such as fast switching and a "wrong" sign of polarization. The results reported enable applications of this polarization effect, including accurate manipulation and control of nuclear fields.
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Affiliation(s)
- J Danon
- Kavli Institute of NanoScience, Delft University of Technology, 2628 CJ Delft, The Netherlands
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