1
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Tyulnev I, Jiménez-Galán Á, Poborska J, Vamos L, Russell PSJ, Tani F, Smirnova O, Ivanov M, Silva REF, Biegert J. Valleytronics in bulk MoS 2 with a topologic optical field. Nature 2024; 628:746-751. [PMID: 38658682 DOI: 10.1038/s41586-024-07156-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 02/02/2024] [Indexed: 04/26/2024]
Abstract
The valley degree of freedom1-4 of electrons in materials promises routes towards energy-efficient information storage with enticing prospects for quantum information processing5-7. Current challenges in utilizing valley polarization are symmetry conditions that require monolayer structures8,9 or specific material engineering10-13, non-resonant optical control to avoid energy dissipation and the ability to switch valley polarization at optical speed. We demonstrate all-optical and non-resonant control over valley polarization using bulk MoS2, a centrosymmetric material without Berry curvature at the valleys. Our universal method utilizes spin angular momentum-shaped trefoil optical control pulses14,15 to switch the material's electronic topology and induce valley polarization by transiently breaking time and space inversion symmetry16 through a simple phase rotation. We confirm valley polarization through the transient generation of the second harmonic of a non-collinear optical probe pulse, depending on the trefoil phase rotation. The investigation shows that direct optical control over the valley degree of freedom is not limited to monolayer structures. Indeed, such control is possible for systems with an arbitrary number of layers and for bulk materials. Non-resonant valley control is universal and, at optical speeds, unlocks the possibility of engineering efficient multimaterial valleytronic devices operating on quantum coherent timescales.
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Affiliation(s)
- Igor Tyulnev
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Álvaro Jiménez-Galán
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
- Max-Born-Institut, Berlin, Germany
| | - Julita Poborska
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Lenard Vamos
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain
| | - Philip St J Russell
- Max-Planck Institute for Science of Light, Erlangen, Germany
- Department of Physics, Friedrich-Alexander-Universität, Erlangen, Germany
| | - Francesco Tani
- Max-Planck Institute for Science of Light, Erlangen, Germany
| | - Olga Smirnova
- Max-Born-Institut, Berlin, Germany
- Technische Universität Berlin, Berlin, Germany
- Technion - Israel Institute of Technology, Haifa, Israel
| | - Misha Ivanov
- Max-Born-Institut, Berlin, Germany
- Technion - Israel Institute of Technology, Haifa, Israel
- Institut für Physik, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Physics, Imperial College London, London, UK
| | - Rui E F Silva
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Jens Biegert
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, Spain.
- ICREA, Barcelona, Spain.
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2
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Craco L, Carara SS, da Silva Barboza E, Milošević MV, Pereira TAS. Electronic and valleytronic properties of crystalline boron-arsenide tuned by strain and disorder. RSC Adv 2023; 13:17907-17913. [PMID: 37323444 PMCID: PMC10262970 DOI: 10.1039/d3ra00898c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/12/2023] [Indexed: 06/17/2023] Open
Abstract
Ab initio density functional theory (DFT) and DFT plus coherent potential approximation (DFT + CPA) are employed to reveal, respectively, the effect of in-plane strain and site-diagonal disorder on the electronic structure of cubic boron arsenide (BAs). It is demonstrated that tensile strain and static diagonal disorder both reduce the semiconducting one-particle band gap of BAs, and a V-shaped p-band electronic state emerges - enabling advanced valleytronics based on strained and disordered semiconducting bulk crystals. At biaxial tensile strains close to 15% the valence band lineshape relevant for optoelectronics is shown to coincide with one reported for GaAs at low energies. The role played by static disorder on the As sites is to promote p-type conductivity in the unstrained BAs bulk crystal, consistent with experimental observations. These findings illuminate the intricate and interdependent changes in crystal structure and lattice disorder on the electronic degrees of freedom of semiconductors and semimetals.
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Affiliation(s)
- L Craco
- Institute of Physics, Federal University of Mato Grosso 78060-900 Cuiabá MT Brazil
| | - S S Carara
- Institute of Physics, Federal University of Mato Grosso 78060-900 Cuiabá MT Brazil
| | - E da Silva Barboza
- Institute of Physics, Federal University of Mato Grosso 78060-900 Cuiabá MT Brazil
| | - M V Milošević
- Institute of Physics, Federal University of Mato Grosso 78060-900 Cuiabá MT Brazil
- Department of Physics, University of Antwerp Groenenborgerlaan 171 2020 Antwerp Belgium
| | - T A S Pereira
- Institute of Physics, Federal University of Mato Grosso 78060-900 Cuiabá MT Brazil
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3
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Ercan HE, Friesen M, Coppersmith SN. Charge-Noise Resilience of Two-Electron Quantum Dots in Si/SiGe Heterostructures. Phys Rev Lett 2022; 128:247701. [PMID: 35776472 DOI: 10.1103/physrevlett.128.247701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 03/30/2022] [Accepted: 04/07/2022] [Indexed: 06/15/2023]
Abstract
The valley degree of freedom presents challenges and opportunities for silicon spin qubits. An important consideration for singlet-triplet states is the presence of two distinct triplets, composed of valley vs orbital excitations. Here, we show that both of these triplets are present in the typical operating regime, but that only the valley-excited triplet offers intrinsic protection against charge noise. We further show that this protection arises naturally in dots with stronger confinement. These results reveal an inherent advantage for silicon-based multielectron qubits.
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Affiliation(s)
- H Ekmel Ercan
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark Friesen
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S N Coppersmith
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
- School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
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4
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Zhou S, Chen K, Cole MT, Li Z, Li M, Chen J, Lienau C, Li C, Dai Q. Ultrafast Electron Tunneling Devices-From Electric-Field Driven to Optical-Field Driven. Adv Mater 2021; 33:e2101449. [PMID: 34240495 DOI: 10.1002/adma.202101449] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 04/05/2021] [Indexed: 06/13/2023]
Abstract
The search for ever higher frequency information processing has become an area of intense research activity within the micro, nano, and optoelectronics communities. Compared to conventional semiconductor-based diffusive transport electron devices, electron tunneling devices provide significantly faster response times due to near-instantaneous tunneling that occurs at sub-femtosecond timescales. As a result, the enhanced performance of electron tunneling devices is demonstrated, time and again, to reimagine a wide variety of traditional electronic devices with a variety of new "lightwave electronics" emerging, each capable of reducing the electron transport channel transit time down to attosecond timescales. In response to unprecedented rapid progress within this field, here the current state-of-the-art in electron tunneling devices is reviewed, current challenges and opportunities are highlighted, and possible future research directions are identified.
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Affiliation(s)
- Shenghan Zhou
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Ke Chen
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Matthew Thomas Cole
- Department of Electronic and Electrical Engineering, University of Bath, Bath, BA2 7AY, UK
| | - Zhenjun Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Mo Li
- School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, P. R. China
| | - Jun Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou, 510275, P. R. China
| | - Christoph Lienau
- Institut für Physik, Center of Interface Science, Carl von Ossietzky Universität, 26129, Oldenburg, Germany
| | - Chi Li
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Qing Dai
- CAS Key Laboratory of Nanophotonic Materials and Devices, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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5
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Banszerus L, Rothstein A, Fabian T, Möller S, Icking E, Trellenkamp S, Lentz F, Neumaier D, Watanabe K, Taniguchi T, Libisch F, Volk C, Stampfer C. Electron-Hole Crossover in Gate-Controlled Bilayer Graphene Quantum Dots. Nano Lett 2020; 20:7709-7715. [PMID: 32986437 PMCID: PMC7564435 DOI: 10.1021/acs.nanolett.0c03227] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/28/2020] [Indexed: 05/21/2023]
Abstract
Electron and hole Bloch states in bilayer graphene exhibit topological orbital magnetic moments with opposite signs, which allows for tunable valley-polarization in an out-of-plane magnetic field. This property makes electron and hole quantum dots (QDs) in bilayer graphene interesting for valley and spin-valley qubits. Here, we show measurements of the electron-hole crossover in a bilayer graphene QD, demonstrating opposite signs of the magnetic moments associated with the Berry curvature. Using three layers of top gates, we independently control the tunneling barriers while tuning the occupation from the few-hole regime to the few-electron regime, crossing the displacement-field-controlled band gap. The band gap is around 25 meV, while the charging energies of the electron and hole dots are between 3 and 5 meV. The extracted valley g-factor is around 17 and leads to opposite valley polarization for electrons and holes at moderate B-fields. Our measurements agree well with tight-binding calculations for our device.
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Affiliation(s)
- L. Banszerus
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - A. Rothstein
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
| | - T. Fabian
- Institute
for Theoretical Physics, TU Wien, 1040 Vienna, Austria, E.U
| | - S. Möller
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - E. Icking
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - S. Trellenkamp
- Helmholtz
Nano Facility, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - F. Lentz
- Helmholtz
Nano Facility, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - D. Neumaier
- AMO
GmbH, Gesellschaft für
Angewandte Mikro- und Optoelektronik, 52074 Aachen, Germany, E.U
- University
of Wuppertal, 42285 Wuppertal, Germany, E.U
| | - 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
| | - F. Libisch
- Institute
for Theoretical Physics, TU Wien, 1040 Vienna, Austria, E.U
| | - C. Volk
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
| | - C. Stampfer
- JARA-FIT
and 2nd Institute of Physics, RWTH Aachen
University, 52074 Aachen, Germany, E.U
- Peter
Grünberg Institute (PGI-9), Forschungszentrum
Jülich, 52425 Jülich, Germany, E.U
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6
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Zhang Z, Gu Y, Long H, Cheng Y, Liu X, Christensen J. Subwavelength Acoustic Valley-Hall Topological Insulators Using Soda Cans Honeycomb Lattices. Research (Wash D C) 2019; 2019:5385763. [PMID: 31549068 PMCID: PMC6750043 DOI: 10.34133/2019/5385763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 07/16/2019] [Indexed: 05/31/2023]
Abstract
Topological valley-contrasting physics has attracted great attention in exploring the use of the valley degree of freedom as a promising carrier of information. Recently, this concept has been extended to acoustic systems to obtain nonbackscattering sound propagations. However, previous demonstrations are limited by the cut-off frequency of 2D waveguides and lattice-scale size restrictions since the topological edge states originate from Bragg interference. Here we engineer topologically valley-projected edge states in the form of spoof surface acoustic waves that confine along the surface of a subwavelength honeycomb lattice composed of 330-mL soda cans. The inversion symmetry is broken through injecting a certain amount of water into one of the two cans in each unit cell, which gaps the Dirac cone and ultimately leads to the topological valley-Hall phase transition. Dual-frequency ranges of the valley-projected edge states below the sound line are observed, which originate from the first-order and second-order resonances, respectively. These results have the potential to enable promising routes to design integrated acoustic devices based on valley-contrasting physics.
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Affiliation(s)
- Zhiwang Zhang
- Department of Physics, MOE Key Laboratory of Modern Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, Universidad Carlos III de Madrid, 28916 Leganés, Madrid, Spain
| | - Ye Gu
- Department of Physics, MOE Key Laboratory of Modern Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Houyou Long
- Department of Physics, MOE Key Laboratory of Modern Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Ying Cheng
- Department of Physics, MOE Key Laboratory of Modern Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiaojun Liu
- Department of Physics, MOE Key Laboratory of Modern Acoustics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Johan Christensen
- Department of Physics, Universidad Carlos III de Madrid, 28916 Leganés, Madrid, Spain
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7
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Goryca M, Wilson NP, Dey P, Xu X, Crooker SA. Detection of thermodynamic "valley noise" in monolayer semiconductors: Access to intrinsic valley relaxation time scales. Sci Adv 2019; 5:eaau4899. [PMID: 30838326 PMCID: PMC6397030 DOI: 10.1126/sciadv.aau4899] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 01/14/2019] [Indexed: 06/09/2023]
Abstract
Together with charge and spin, many novel two-dimensional materials also permit information to be encoded in an electron's valley degree of freedom-that is, in particular momentum states in the material's Brillouin zone. With a view toward valley-based (opto)electronic technologies, the intrinsic time scales of valley scattering are therefore of fundamental interest. Here, we demonstrate an entirely noise-based approach for exploring valley dynamics in monolayer transition-metal dichalcogenide semiconductors. Exploiting their valley-specific optical selection rules, we use optical Faraday rotation to passively detect the thermodynamic fluctuations of valley polarization in a Fermi sea of resident carriers. This spontaneous "valley noise" reveals narrow Lorentzian line shapes and, therefore, long exponentially-decaying intrinsic valley relaxation. Moreover, the noise signatures validate both the relaxation times and the spectral dependence of conventional (perturbative) pump-probe measurements. These results provide a viable route toward quantitative measurements of intrinsic valley dynamics, free from any external perturbation, pumping, or excitation.
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Affiliation(s)
- M. Goryca
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
- Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - N. P. Wilson
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - P. Dey
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
| | - X. Xu
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - S. A. Crooker
- National High Magnetic Field Laboratory, Los Alamos, NM 87545, USA
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8
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Abstract
We study an accumulation mode Si/SiGe double quantum dot (DQD) containing a single electron that is dipole coupled to microwave photons in a superconducting cavity. Measurements of the cavity transmission reveal dispersive features due to the DQD valley states in Si. The occupation of the valley states can be increased by raising the temperature or applying a finite source-drain bias across the DQD, resulting in an increased signal. Using the cavity input-output theory and a four-level model of the DQD, it is possible to efficiently extract valley splittings and the inter- and intravalley tunnel couplings.
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Affiliation(s)
- X Mi
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Csaba G Péterfalvi
- Department of Physics, University of Konstanz, D-78464 Konstanz, Germany
| | - Guido Burkard
- Department of Physics, University of Konstanz, D-78464 Konstanz, Germany
| | - J R Petta
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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9
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Abstract
The goal of this article is to review the progress of three-electron spin qubits from their inception to the state of the art. We direct the main focus towards the exchange-only qubit (Bacon et al 2000 Phys. Rev. Lett. 85 1758-61, DiVincenzo et al 2000 Nature 408 339) and its derived versions, e.g. the resonant exchange (RX) qubit, but we also discuss other qubit implementations using three electron spins. For each three-spin qubit we describe the qubit model, the envisioned physical realization, the implementations of single-qubit operations, as well as the read-out and initialization schemes. Two-qubit gates and decoherence properties are discussed for the RX qubit and the exchange-only qubit, thereby completing the list of requirements for quantum computation for a viable candidate qubit implementation. We start by describing the full system of three electrons in a triple quantum dot, then discuss the charge-stability diagram, restricting ourselves to the relevant subsystem, introduce the qubit states, and discuss important transitions to other charge states (Russ et al 2016 Phys. Rev. B 94 165411). Introducing the various qubit implementations, we begin with the exchange-only qubit (DiVincenzo et al 2000 Nature 408 339, Laird et al 2010 Phys. Rev. B 82 075403), followed by the RX qubit (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502), the spin-charge qubit (Kyriakidis and Burkard 2007 Phys. Rev. B 75 115324), and the hybrid qubit (Shi et al 2012 Phys. Rev. Lett. 108 140503, Koh et al 2012 Phys. Rev. Lett. 109 250503, Cao et al 2016 Phys. Rev. Lett. 116 086801, Thorgrimsson et al 2016 arXiv:1611.04945). The main focus will be on the exchange-only qubit and its modification, the RX qubit, whose single-qubit operations are realized by driving the qubit at its resonant frequency in the microwave range similar to electron spin resonance. Two different types of two-qubit operations are presented for the exchange-only qubits which can be divided into short-ranged and long-ranged interactions. Both of these interaction types are expected to be necessary in a large-scale quantum computer. The short-ranged interactions use the exchange coupling by placing qubits next to each other and applying exchange-pulses (DiVincenzo et al 2000 Nature 408 339, Fong and Wandzura 2011 Quantum Inf. Comput. 11 1003, Setiawan et al 2014 Phys. Rev. B 89 085314, Zeuch et al 2014 Phys. Rev. B 90 045306, Doherty and Wardrop 2013 Phys. Rev. Lett. 111 050503, Shim and Tahan 2016 Phys. Rev. B 93 121410), while the long-ranged interactions use the photons of a superconducting microwave cavity as a mediator in order to couple two qubits over long distances (Russ and Burkard 2015 Phys. Rev. B 92 205412, Srinivasa et al 2016 Phys. Rev. B 94 205421). The nature of the three-electron qubit states each having the same total spin and total spin in z-direction (same Zeeman energy) provides a natural protection against several sources of noise (DiVincenzo et al 2000 Nature 408 339, Taylor et al 2013 Phys. Rev. Lett. 111 050502, Kempe et al 2001 Phys. Rev. A 63 042307, Russ and Burkard 2015 Phys. Rev. B 91 235411). The price to pay for this advantage is an increase in gate complexity. We also take into account the decoherence of the qubit through the influence of magnetic noise (Ladd 2012 Phys. Rev. B 86 125408, Mehl and DiVincenzo 2013 Phys. Rev. B 87 195309, Hung et al 2014 Phys. Rev. B 90 045308), in particular dephasing due to the presence of nuclear spins, as well as dephasing due to charge noise (Medford et al 2013 Phys. Rev. Lett. 111 050501, Taylor et al 2013 Phys. Rev. Lett. 111 050502, Shim and Tahan 2016 Phys. Rev. B 93 121410, Russ and Burkard 2015 Phys. Rev. B 91 235411, Fei et al 2015 Phys. Rev. B 91 205434), fluctuations of the energy levels on each dot due to noisy gate voltages or the environment. Several techniques are discussed which partly decouple the qubit from magnetic noise (Setiawan et al 2014 Phys. Rev. B 89 085314, West and Fong 2012 New J. Phys. 14 083002, Rohling and Burkard 2016 Phys. Rev. B 93 205434) while for charge noise it is shown that it is favorable to operate the qubit on the so-called '(double) sweet spots' (Taylor et al 2013 Phys. Rev. Lett. 111 050502, Shim and Tahan 2016 Phys. Rev. B 93 121410, Russ and Burkard 2015 Phys. Rev. B 91 235411, Fei et al 2015 Phys. Rev. B 91 205434, Malinowski et al 2017 arXiv: 1704.01298), which are least susceptible to noise, thus providing a longer lifetime of the qubit.
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Affiliation(s)
- Maximilian Russ
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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10
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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11
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Neumann A, Lindlau J, Colombier L, Nutz M, Najmaei S, Lou J, Mohite AD, Yamaguchi H, Högele A. Opto-valleytronic imaging of atomically thin semiconductors. Nat Nanotechnol 2017; 12:329-334. [PMID: 28092378 DOI: 10.1038/nnano.2016.282] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 11/27/2016] [Indexed: 06/06/2023]
Abstract
Transition metal dichalcogenide semiconductors represent elementary components of layered heterostructures for emergent technologies beyond conventional optoelectronics. In their monolayer form they host electrons with quantized circular motion and associated valley polarization and valley coherence as key elements of opto-valleytronic functionality. Here, we introduce two-dimensional polarimetry as means of direct imaging of the valley pseudospin degree of freedom in monolayer transition metal dichalcogenides. Using MoS2 as a representative material with valley-selective optical transitions, we establish quantitative image analysis for polarimetric maps of extended crystals, and identify valley polarization and valley coherence as sensitive probes of crystalline disorder. Moreover, we find site-dependent thermal and non-thermal regimes of valley-polarized excitons in perpendicular magnetic fields. Finally, we demonstrate the potential of wide-field polarimetry for rapid inspection of opto-valleytronic devices based on atomically thin semiconductors and heterostructures.
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Affiliation(s)
- Andre Neumann
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München, Germany
| | - Jessica Lindlau
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München, Germany
| | - Léo Colombier
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München, Germany
| | - Manuel Nutz
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München, Germany
| | - Sina Najmaei
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Jun Lou
- Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA
| | - Aditya D Mohite
- MPA-11 Materials Synthesis and Integrated Devices, Materials Physics and Applications Division, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, USA
| | - Hisato Yamaguchi
- MPA-11 Materials Synthesis and Integrated Devices, Materials Physics and Applications Division, Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, USA
| | - Alexander Högele
- Fakultät für Physik, Munich Quantum Center, and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, D-80539 München, Germany
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12
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Tettamanzi GC, Hile SJ, House MG, Fuechsle M, Rogge S, Simmons MY. Probing the Quantum States of a Single Atom Transistor at Microwave Frequencies. ACS Nano 2017; 11:2444-2451. [PMID: 28351121 DOI: 10.1021/acsnano.6b06362] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The ability to apply gigahertz frequencies to control the quantum state of a single P atom is an essential requirement for the fast gate pulsing needed for qubit control in donor-based silicon quantum computation. Here, we demonstrate this with nanosecond accuracy in an all epitaxial single atom transistor by applying excitation signals at frequencies up to ≈13 GHz to heavily phosphorus-doped silicon leads. These measurements allow the differentiation between the excited states of the single atom and the density of states in the one-dimensional leads. Our pulse spectroscopy experiments confirm the presence of an excited state at an energy ≈9 meV, consistent with the first excited state of a single P donor in silicon. The relaxation rate of this first excited state to the ground state is estimated to be larger than 2.5 GHz, consistent with theoretical predictions. These results represent a systematic investigation of how an atomically precise single atom transistor device behaves under radio frequency excitations.
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Affiliation(s)
- Giuseppe Carlo Tettamanzi
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Samuel James Hile
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Matthew Gregory House
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Martin Fuechsle
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Sven Rogge
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Michelle Y Simmons
- School of Physics and Centre of Excellence for Quantum Computation and Communication Technology, UNSW Australia , Sydney, New South Wales 2052, Australia
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13
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Abstract
It is shown that the degeneracy of the bandstructure has different impacts on thermoelectric properties of III–V materials.
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Affiliation(s)
- Payam Norouzzadeh
- Electrical and Computer Engineering Department
- North Carolina State University
- Raleigh
- USA
| | - Ali Shakouri
- Birck Nanotechnology Center
- Purdue University
- West Lafayette
- USA
| | - Daryoosh Vashaee
- Electrical and Computer Engineering Department
- North Carolina State University
- Raleigh
- USA
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14
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Čukarić NA, Partoens B, Tadić MŽ, Arsoski VV, Peeters FM. The 30-band k ⋅ p theory of valley splitting in silicon thin layers. J Phys Condens Matter 2016; 28:195303. [PMID: 27093609 DOI: 10.1088/0953-8984/28/19/195303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The valley splitting of the conduction-band states in a thin silicon-on-insulator layer is investigated using the 30-band k ⋅ p theory. The system composed of a few nm thick [Formula: see text] layer embedded within thick SiO2 layers is analyzed. The valley split states are found to cross periodically with increasing quantum well width, and therefore the energy splitting is an oscillatory function of the quantum well width, with period determined by the wave vector K 0 of the conduction band minimum. Because the valley split states are classified by parity, the optical transition between the ground hole state and one of those valley split conduction band states is forbidden. The oscillations in the valley splitting energy decrease with electric field and with smoothing of the composition profile between the well and the barrier by diffusion of oxygen from the SiO2 layers to the Si quantum well. Such a smoothing also leads to a decrease of the interband transition matrix elements. The obtained results are well parametrized by the effective two-valley model, but are found to disagree from previous 30-band calculations. This discrepancy could be traced back to the fact that the basis for the numerical solution of the eigenproblem must be restricted to the first Brillouin zone in order to obtain quantitatively correct results for the valley splitting.
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Affiliation(s)
- Nemanja A Čukarić
- School of Electrical Engineering, University of Belgrade, PO Box 35-54, 11120 Belgrade, Serbia
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15
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Reed MD, Maune BM, Andrews RW, Borselli MG, Eng K, Jura MP, Kiselev AA, Ladd TD, Merkel ST, Milosavljevic I, Pritchett EJ, Rakher MT, Ross RS, Schmitz AE, Smith A, Wright JA, Gyure MF, Hunter AT. Reduced Sensitivity to Charge Noise in Semiconductor Spin Qubits via Symmetric Operation. Phys Rev Lett 2016; 116:110402. [PMID: 27035289 DOI: 10.1103/physrevlett.116.110402] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate improved operation of exchange-coupled semiconductor quantum dots by substantially reducing the sensitivity of exchange operations to charge noise. The method involves biasing a double dot symmetrically between the charge-state anticrossings, where the derivative of the exchange energy with respect to gate voltages is minimized. Exchange remains highly tunable by adjusting the tunnel coupling. We find that this method reduces the dephasing effect of charge noise by more than a factor of 5 in comparison to operation near a charge-state anticrossing, increasing the number of observable exchange oscillations in our qubit by a similar factor. Performance also improves with exchange rate, favoring fast quantum operations.
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Affiliation(s)
- M D Reed
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - B M Maune
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - R W Andrews
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - M G Borselli
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - K Eng
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - M P Jura
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - A A Kiselev
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - T D Ladd
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - S T Merkel
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - I Milosavljevic
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - E J Pritchett
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - M T Rakher
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - R S Ross
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - A E Schmitz
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - A Smith
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - J A Wright
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - M F Gyure
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
| | - A T Hunter
- HRL Laboratories, LLC, 3011 Malibu Canyon Road, Malibu, California 90265, USA
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16
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Abstract
The theory of valleytronics as a material design tool for engineering both thermal and electrical transport properties is presented. It is shown that the interplay among the valleytronics parameters such as the degeneracy of the band, intervalley transitions, effective mass, scattering exponent, and the Fermi energy may deteriorate or ameliorate any or all of the main thermoelectric properties. A flowchart classifying the different paths through which the valleytronics can influence the thermoelectric figure-of-merit ZT is derived and discussed in detail. To exemplify the application of the flowchart, valleytronics in four different semiconductors, Mg2Si, Si0.8Ge0.2, AlxGa1−xAs and clathrate Si46-VIII were studied, which showed different trends. Therefore, a degenerate multivalley bandstructure, which is typically anticipated for a good thermoelectric material, cannot be a general design rule for ZT enhancement and a detailed transport study is required to engineer the optimum bandstructure.
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Affiliation(s)
- Payam Norouzzadeh
- Electrical and Computer Engineering Department, Montheith Research Center, North Carolina State University, Raleigh, NC 27606, USA
| | - Daryoosh Vashaee
- Electrical and Computer Engineering Department, Montheith Research Center, North Carolina State University, Raleigh, NC 27606, USA
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17
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Renard VT, Piot BA, Waintal X, Fleury G, Cooper D, Niida Y, Tregurtha D, Fujiwara A, Hirayama Y, Takashina K. Valley polarization assisted spin polarization in two dimensions. Nat Commun 2015; 6:7230. [PMID: 26027889 PMCID: PMC4458877 DOI: 10.1038/ncomms8230] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 04/20/2015] [Indexed: 11/15/2022] Open
Abstract
Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.
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Affiliation(s)
- V. T. Renard
- Université Grenoble Alpes/CEA, INAC-SPSMS, F-38000, Grenoble, France
| | - B. A. Piot
- Laboratoire National des Champs Magnétiques Intenses, CNRS-UJF-UPS-INSA-EMFL, 38042, Grenoble, France
| | - X. Waintal
- Université Grenoble Alpes/CEA, INAC-SPSMS, F-38000, Grenoble, France
| | - G. Fleury
- Service de Physique de l'État Condensé, DSM/IRAMIS/SPEC, CNRS UMR 3680 CEA Saclay, 91191 Gif sur Yvette, France
| | - D. Cooper
- Université Grenoble Alpes/CEA Leti Minatec campus, F-38054, Grenoble, France
| | - Y. Niida
- Graduate School of Science, Tohoku University, 6-3 Aramakiaza Aoba, Aobaku, Sendai, 980-8578, Japan
| | - D. Tregurtha
- Department of Physics, University of Bath, Bath, BA2 7AY, UK
| | - A. Fujiwara
- NTT Basic Research Laboratories, NTT Corporation, Atsugi-shi, Kanagawa, 243-0198, Japan
| | - Y. Hirayama
- Graduate School of Science, Tohoku University, 6-3 Aramakiaza Aoba, Aobaku, Sendai, 980-8578, Japan
| | - K. Takashina
- Department of Physics, University of Bath, Bath, BA2 7AY, UK
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18
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Noborisaka J, Nishiguchi K, Fujiwara A. Electric tuning of direct-indirect optical transitions in silicon. Sci Rep 2014; 4:6950. [PMID: 25377598 DOI: 10.1038/srep06950] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 10/13/2014] [Indexed: 11/08/2022] Open
Abstract
Electronic band structures in semiconductors are uniquely determined by the constituent elements of the lattice. For example, bulk silicon has an indirect bandgap and it prohibits efficient light emission. Here we report the electrical tuning of the direct/indirect band optical transition in an ultrathin silicon-on-insulator (SOI) gated metal-oxide-semiconductor (MOS) light-emitting diode. A special Si/SiO2 interface formed by high-temperature annealing that shows stronger valley coupling enables us to observe phononless direct optical transition. Furthermore, by controlling the gate field, its strength can be electrically tuned to 16 times that of the indirect transition, which is nearly 800 times larger than the weak direct transition in bulk silicon. These results will therefore assist the development of both complementary MOS (CMOS)-compatible silicon photonics and the emerging "valleytronics" based on the control of the valley degree of freedom.
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19
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Abstract
The valley degree of freedom in the electronic band structure of silicon, graphene, and other materials is often considered to be an obstacle for quantum computing (QC) based on electron spins in quantum dots. Here we show that control over the valley state opens new possibilities for quantum information processing. Combining qubits encoded in the singlet-triplet subspace of spin and valley states allows for universal QC using a universal two-qubit gate directly provided by the exchange interaction. We show how spin and valley qubits can be separated in order to allow for single-qubit rotations.
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Affiliation(s)
- Niklas Rohling
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Maximilian Russ
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - Guido Burkard
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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20
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Salfi J, Mol JA, Rahman R, Klimeck G, Simmons MY, Hollenberg LCL, Rogge S. Spatially resolving valley quantum interference of a donor in silicon. Nat Mater 2014; 13:605-10. [PMID: 24705384 DOI: 10.1038/nmat3941] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 03/07/2014] [Indexed: 05/27/2023]
Abstract
Electron and nuclear spins of donor ensembles in isotopically pure silicon experience a vacuum-like environment, giving them extraordinary coherence. However, in contrast to a real vacuum, electrons in silicon occupy quantum superpositions of valleys in momentum space. Addressable single-qubit and two-qubit operations in silicon require that qubits are placed near interfaces, modifying the valley degrees of freedom associated with these quantum superpositions and strongly influencing qubit relaxation and exchange processes. Yet to date, spectroscopic measurements have only probed wavefunctions indirectly, preventing direct experimental access to valley population, donor position and environment. Here we directly probe the probability density of single quantum states of individual subsurface donors, in real space and reciprocal space, using scanning tunnelling spectroscopy. We directly observe quantum mechanical valley interference patterns associated with linear superpositions of valleys in the donor ground state. The valley population is found to be within 5% of a bulk donor when 2.85 ± 0.45 nm from the interface, indicating that valley-perturbation-induced enhancement of spin relaxation will be negligible for depths greater than 3 nm. The observed valley interference will render two-qubit exchange gates sensitive to atomic-scale variations in positions of subsurface donors. Moreover, these results will also be of interest for emerging schemes proposing to encode information directly in valley polarization.
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Affiliation(s)
- J Salfi
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J A Mol
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - R Rahman
- Purdue University, West Lafayette, Indiana 47906, USA
| | - G Klimeck
- Purdue University, West Lafayette, Indiana 47906, USA
| | - M Y Simmons
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - L C L Hollenberg
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - S Rogge
- Centre for Quantum Computation and Communication Technology, School of Physics, The University of New South Wales, Sydney, New South Wales 2052, Australia
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21
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Hao X, Ruskov R, Xiao M, Tahan C, Jiang H. Electron spin resonance and spin–valley physics in a silicon double quantum dot. Nat Commun 2014; 5:3860. [DOI: 10.1038/ncomms4860] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 04/11/2014] [Indexed: 11/09/2022] Open
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22
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Lee S, Lee Y, Song EB, Hiramoto T. Observation of single electron transport via multiple quantum states of a silicon quantum dot at room temperature. Nano Lett 2014; 14:71-77. [PMID: 24289317 DOI: 10.1021/nl403204k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Single electron transport through multiple quantum levels is realized in a Si quantum-dot device at room-temperature conditions. The energy spacing of more than triple the omnipresent thermal energy is obtained from an extremely small ellipsoidal Si quantum dot, and high charge stability is attained through a construction of the gate-all-around structure. These properties may move us a step closer to practical applications of quantum devices at elevated temperatures. An in-depth analysis on the transport behavior and quantum structure is presented.
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Affiliation(s)
- Sejoon Lee
- Department of Semiconductor Science, Dongguk University-Seoul , Seoul 100-715, Korea
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23
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Yang CH, Rossi A, Ruskov R, Lai NS, Mohiyaddin FA, Lee S, Tahan C, Klimeck G, Morello A, Dzurak AS. Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting. Nat Commun 2013; 4. [DOI: 10.1038/ncomms3069] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Accepted: 05/27/2013] [Indexed: 12/12/2022] Open
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24
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Abstract
Single donor atoms in semiconductor nanostructures are attractive basic components for quantum device applications. In this work, we demonstrate the ability to manipulate the wave function of a single donor electron with an electric field. The deformation of the wave function is probed by the tunnel current which, furthermore, allows for the determination of the location of the atom in the device. This experiment demonstrates the control necessary for the utilization of single donors in quantum electronics.
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Affiliation(s)
- J Verduijn
- Centre for Quantum Computation and Communication Technology, University of New South Wales, Sydney, NSW 2052, Australia.
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25
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Renard VT, Duchemin I, Niida Y, Fujiwara A, Hirayama Y, Takashina K. Metallic behaviour in SOI quantum wells with strong intervalley scattering. Sci Rep 2013; 3:2011. [PMID: 23774638 PMCID: PMC3684805 DOI: 10.1038/srep02011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 05/31/2013] [Indexed: 11/09/2022] Open
Abstract
The fundamental properties of valleys are recently attracting growing attention due to electrons in new and topical materials possessing this degree-of-freedom and recent proposals for valleytronics devices. In silicon MOSFETs, the interest has a longer history since the valley degree of freedom had been identified as a key parameter in the observation of the controversial "metallic behaviour" in two dimensions. However, while it has been recently demonstrated that lifting valley degeneracy can destroy the metallic behaviour, little is known about the role of intervalley scattering. Here, we show that the metallic behaviour can be observed in the presence of strong intervalley scattering in silicon on insulator (SOI) quantum wells. Analysis of the conductivity in terms of quantum corrections reveals that interactions are much stronger in SOI than in conventional MOSFETs, leading to the metallic behaviour despite the strong intervalley scattering.
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Affiliation(s)
- V T Renard
- SPSMS, UMR-E 9001, CEA-INAC/UJF-Grenoble 1, INAC, Grenoble, France.
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