151
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Baart TA, Shafiei M, Fujita T, Reichl C, Wegscheider W, Vandersypen LMK. Single-spin CCD. NATURE NANOTECHNOLOGY 2016; 11:330-334. [PMID: 26727201 DOI: 10.1038/nnano.2015.291] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/11/2015] [Indexed: 06/05/2023]
Abstract
Spin-based electronics or spintronics relies on the ability to store, transport and manipulate electron spin polarization with great precision. In its ultimate limit, information is stored in the spin state of a single electron, at which point quantum information processing also becomes a possibility. Here, we demonstrate the manipulation, transport and readout of individual electron spins in a linear array of three semiconductor quantum dots. First, we demonstrate single-shot readout of three spins with fidelities of 97% on average, using an approach analogous to the operation of a charge-coupled device (CCD). Next, we perform site-selective control of the three spins, thereby writing the content of each pixel of this 'single-spin charge-coupled device'. Finally, we show that shuttling an electron back and forth in the array hundreds of times, covering a cumulative distance of 80 μm, has negligible influence on its spin projection. Extrapolating these results to the case of much larger arrays points at a diverse range of potential applications, from quantum information to imaging and sensing.
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Affiliation(s)
- T A Baart
- QuTech and Kavli Institute of Nanoscience, TU Delft, GA Delft 2600, The Netherlands
| | - M Shafiei
- QuTech and Kavli Institute of Nanoscience, TU Delft, GA Delft 2600, The Netherlands
| | - T Fujita
- QuTech and Kavli Institute of Nanoscience, TU Delft, GA Delft 2600, The Netherlands
| | - C Reichl
- Solid State Physics Laboratory, ETH Zürich, Zürich 8093, Switzerland
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zürich, Zürich 8093, Switzerland
| | - L M K Vandersypen
- QuTech and Kavli Institute of Nanoscience, TU Delft, GA Delft 2600, The Netherlands
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152
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Fernandez A, Ferrando-Soria J, Pineda EM, Tuna F, Vitorica-Yrezabal IJ, Knappke C, Ujma J, Muryn CA, Timco GA, Barran PE, Ardavan A, Winpenny RE. Making hybrid [n]-rotaxanes as supramolecular arrays of molecular electron spin qubits. Nat Commun 2016; 7:10240. [PMID: 26742716 PMCID: PMC4729860 DOI: 10.1038/ncomms10240] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 11/17/2015] [Indexed: 02/04/2023] Open
Abstract
Quantum information processing (QIP) would require that the individual units involved--qubits--communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic-inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2C(t)Bu)16](-) coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron-electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates.
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Affiliation(s)
- Antonio Fernandez
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Jesus Ferrando-Soria
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Eufemio Moreno Pineda
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Floriana Tuna
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Iñigo J. Vitorica-Yrezabal
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | | | - Jakub Ujma
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
- The Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Christopher A. Muryn
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Grigore A. Timco
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Perdita E. Barran
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
- The Michael Barber Centre for Collaborative Mass Spectrometry, Manchester Institute of Biotechnology, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Arzhang Ardavan
- Department of Physics, Centre for Advanced Electron Spin Resonance, The Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Richard E.P. Winpenny
- School of Chemistry and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
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153
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Dasog M, Kehrle J, Rieger B, Veinot JGC. Silicon Nanocrystals and Silicon-Polymer Hybrids: Synthesis, Surface Engineering, and Applications. Angew Chem Int Ed Engl 2015; 55:2322-39. [DOI: 10.1002/anie.201506065] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 09/18/2015] [Indexed: 12/16/2022]
Affiliation(s)
- Mita Dasog
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 East California Boulevard Pasadena CA 91125 USA
| | - Julian Kehrle
- WACKER-Lehrstuhl für Makromolekulare Chemie; Technische Universität München; Lichtenbergstrasse 4 85747 Garching Germany
| | - Bernhard Rieger
- WACKER-Lehrstuhl für Makromolekulare Chemie; Technische Universität München; Lichtenbergstrasse 4 85747 Garching Germany
| | - Jonathan G. C. Veinot
- Department of Chemistry; University of Alberta; 11227 Saskatchewan Drive Edmonton Alberta T6G 2G2 Canada
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154
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Dasog M, Kehrle J, Rieger B, Veinot JGC. Silicium-Nanokristalle und Silicium-Polymer-Hybridmaterialien: Synthese, Oberflächenmodifikation und Anwendungen. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506065] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Mita Dasog
- Division of Chemistry and Chemical Engineering; California Institute of Technology; 1200 East California Boulevard Pasadena CA 91125 USA
| | - Julian Kehrle
- WACKER-Lehrstuhl für Makromolekulare Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Bernhard Rieger
- WACKER-Lehrstuhl für Makromolekulare Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Jonathan G. C. Veinot
- Department of Chemistry; University of Alberta; 11227 Saskatchewan Drive Edmonton Alberta T6G 2G2 Kanada
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155
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Li R, Hudson FE, Dzurak AS, Hamilton AR. Pauli Spin Blockade of Heavy Holes in a Silicon Double Quantum Dot. NANO LETTERS 2015; 15:7314-8. [PMID: 26434407 DOI: 10.1021/acs.nanolett.5b02561] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In this work, we study hole transport in a planar silicon metal-oxide-semiconductor based double quantum dot. We demonstrate Pauli spin blockade in the few hole regime and map the spin relaxation induced leakage current as a function of interdot level spacing and magnetic field. With varied interdot tunnel coupling, we can identify different dominant spin relaxation mechanisms. Application of a strong out-of-plane magnetic field causes an avoided singlet-triplet level crossing, from which the heavy hole g-factor ~0.93 and the strength of spin-orbit interaction ~110 μeV can be obtained. The demonstrated strong spin-orbit interaction of heavy holes promises fast local spin manipulation using only electric fields, which is of great interest for quantum information processing.
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Affiliation(s)
- Ruoyu Li
- School of Physics, ‡Australian National Fabrication Facility, and §Centre of Excellence for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Fay E Hudson
- School of Physics, ‡Australian National Fabrication Facility, and §Centre of Excellence for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Andrew S Dzurak
- School of Physics, ‡Australian National Fabrication Facility, and §Centre of Excellence for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Alexander R Hamilton
- School of Physics, ‡Australian National Fabrication Facility, and §Centre of Excellence for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, University of New South Wales , Sydney, New South Wales 2052, Australia
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156
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Watson TF, Weber B, House MG, Büch H, Simmons MY. High-Fidelity Rapid Initialization and Read-Out of an Electron Spin via the Single Donor D(-) Charge State. PHYSICAL REVIEW LETTERS 2015; 115:166806. [PMID: 26550896 DOI: 10.1103/physrevlett.115.166806] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Indexed: 05/14/2023]
Abstract
We demonstrate high-fidelity electron spin read-out of a precision placed single donor in silicon via spin selective tunneling to either the D(+) or D(-) charge state of the donor. By performing read-out at the stable two electron D(0)↔D(-) charge transition we can increase the tunnel rates to a nearby single electron transistor charge sensor by nearly 2 orders of magnitude, allowing faster qubit read-out (1 ms) with minimum loss in read-out fidelity (98.4%) compared to read-out at the D(+)↔D(0) transition (99.6%). Furthermore, we show that read-out via the D(-) charge state can be used to rapidly initialize the electron spin qubit in its ground state with a fidelity of F(I)=99.8%.
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Affiliation(s)
- T F Watson
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - B Weber
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - M G House
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - H Büch
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - M Y Simmons
- Australian Research Council Centre of Excellence for Quantum Computation and Communication Technology, University of New South Wales, Sydney, New South Wales 2052, Australia
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157
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Abstract
Quantum computation requires qubits that can be coupled in a scalable manner, together with universal and high-fidelity one- and two-qubit logic gates. Many physical realizations of qubits exist, including single photons, trapped ions, superconducting circuits, single defects or atoms in diamond and silicon, and semiconductor quantum dots, with single-qubit fidelities that exceed the stringent thresholds required for fault-tolerant quantum computing. Despite this, high-fidelity two-qubit gates in the solid state that can be manufactured using standard lithographic techniques have so far been limited to superconducting qubits, owing to the difficulties of coupling qubits and dephasing in semiconductor systems. Here we present a two-qubit logic gate, which uses single spins in isotopically enriched silicon and is realized by performing single- and two-qubit operations in a quantum dot system using the exchange interaction, as envisaged in the Loss-DiVincenzo proposal. We realize CNOT gates via controlled-phase operations combined with single-qubit operations. Direct gate-voltage control provides single-qubit addressability, together with a switchable exchange interaction that is used in the two-qubit controlled-phase gate. By independently reading out both qubits, we measure clear anticorrelations in the two-spin probabilities of the CNOT gate.
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158
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Otsuka T, Amaha S, Nakajima T, Delbecq MR, Yoneda J, Takeda K, Sugawara R, Allison G, Ludwig A, Wieck AD, Tarucha S. Fast probe of local electronic states in nanostructures utilizing a single-lead quantum dot. Sci Rep 2015; 5:14616. [PMID: 26416582 PMCID: PMC4586608 DOI: 10.1038/srep14616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/02/2015] [Indexed: 11/30/2022] Open
Abstract
Transport measurements are powerful tools to probe electronic properties of solid-state materials. To access properties of local electronic states in nanostructures, such as local density of states, electronic distribution and so on, micro-probes utilizing artificial nanostructures have been invented to perform measurements in addition to those with conventional macroscopic electronic reservoirs. Here we demonstrate a new kind of micro-probe: a fast single-lead quantum dot probe, which utilizes a quantum dot coupled only to the target structure through a tunneling barrier and fast charge readout by RF reflectometry. The probe can directly access the local electronic states with wide bandwidth. The probe can also access more electronic states, not just those around the Fermi level, and the operations are robust against bias voltages and temperatures.
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Affiliation(s)
- Tomohiro Otsuka
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Shinichi Amaha
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takashi Nakajima
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Matthieu R Delbecq
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Jun Yoneda
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Kenta Takeda
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Retsu Sugawara
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Giles Allison
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Arne Ludwig
- Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Andreas D Wieck
- Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - Seigo Tarucha
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.,Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.,Quantum-Phase Electronics Center, University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan.,Institute for Nano Quantum Information Electronics, University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
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159
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Scarlino P, Kawakami E, Ward DR, Savage DE, Lagally MG, Friesen M, Coppersmith SN, Eriksson MA, Vandersypen LMK. Second-Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot. PHYSICAL REVIEW LETTERS 2015; 115:106802. [PMID: 26382693 DOI: 10.1103/physrevlett.115.106802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Indexed: 06/05/2023]
Abstract
We demonstrate coherent driving of a single electron spin using second-harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second-harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude, and the periodicity with respect to the phase of the drive is twice that of the fundamental harmonic. The maximum Rabi frequency observed for the second harmonic is just a factor of 2 lower than that achieved for the first harmonic when driving at the same power. Combined with the lower demands on microwave circuitry when operating at half the qubit frequency, these observations indicate that second-harmonic driving can be a useful technique for future quantum computation architectures.
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Affiliation(s)
- P Scarlino
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - E Kawakami
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - D R Ward
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - D E Savage
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M G Lagally
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark Friesen
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S N Coppersmith
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M A Eriksson
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - L M K Vandersypen
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
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160
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Biesinger DEF, Scheller CP, Braunecker B, Zimmerman J, Gossard AC, Zumbühl DM. Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot. PHYSICAL REVIEW LETTERS 2015; 115:106804. [PMID: 26382695 DOI: 10.1103/physrevlett.115.106804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Indexed: 06/05/2023]
Abstract
We report a thermally activated metastability in a GaAs double quantum dot exhibiting real-time charge switching in diamond shaped regions of the charge stability diagram. Accidental charge traps and sensor backaction are excluded as the origin of the switching. We present an extension of the canonical double dot theory based on an intrinsic, thermal electron exchange process through the reservoirs, giving excellent agreement with the experiment. The electron spin is randomized by the exchange process, thus facilitating fast, gate-controlled spin initialization. At the same time, this process sets an intrinsic upper limit to the spin relaxation time.
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Affiliation(s)
- D E F Biesinger
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - C P Scheller
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
- Swiss Federal Laboratories for Materials Science and Technology, EMPA, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - B Braunecker
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United Kingdom
| | - J Zimmerman
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - A C Gossard
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - D M Zumbühl
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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161
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Bertrand B, Flentje H, Takada S, Yamamoto M, Tarucha S, Ludwig A, Wieck AD, Bäuerle C, Meunier T. Quantum Manipulation of Two-Electron Spin States in Isolated Double Quantum Dots. PHYSICAL REVIEW LETTERS 2015; 115:096801. [PMID: 26371672 DOI: 10.1103/physrevlett.115.096801] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 06/05/2023]
Abstract
We studied experimentally the dynamics of the exchange interaction between two antiparallel electron spins in an isolated double quantum dot where coupling to the electron reservoirs can be ignored. We demonstrate that the level of control of such a double dot is higher than in conventional double dots. In particular, it allows us to couple coherently two electron spins in an efficient manner following a scheme initially proposed by Loss and DiVincenzo [Phys. Rev. A 57, 120 (1998)]. The present study demonstrates that isolated quantum dots are a possible route to increase the number of coherently coupled quantum dots.
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Affiliation(s)
- Benoit Bertrand
- Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - Hanno Flentje
- Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - Shintaro Takada
- Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
| | - Michihisa Yamamoto
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
- PRESTO-JST, Kawaguchi-shi, Saitama 331-0012, Japan
| | - Seigo Tarucha
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-Shi, Saitama 31-0198, Japan
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Christopher Bäuerle
- Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
| | - Tristan Meunier
- Université Grenoble Alpes, Institut NEEL, F-38042 Grenoble, France
- CNRS, Institut NEEL, F-38042 Grenoble, France
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162
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Mueller F, Konstantaras G, Spruijtenburg PC, van der Wiel WG, Zwanenburg FA. Electron-Hole Confinement Symmetry in Silicon Quantum Dots. NANO LETTERS 2015; 15:5336-5341. [PMID: 26134900 DOI: 10.1021/acs.nanolett.5b01706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report electrical transport measurements on a gate-defined ambipolar quantum dot in intrinsic silicon. The ambipolarity allows its operation as either an electron or a hole quantum dot of which we change the dot occupancy by 20 charge carriers in each regime. Electron-hole confinement symmetry is evidenced by the extracted gate capacitances and charging energies. The results demonstrate that ambipolar quantum dots offer great potential for spin-based quantum information processing, since confined electrons and holes can be compared and manipulated in the same crystalline environment.
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Affiliation(s)
- Filipp Mueller
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Georgios Konstantaras
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Paul C Spruijtenburg
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Wilfred G van der Wiel
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Floris A Zwanenburg
- NanoElectronics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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163
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Quantum Phase Coherence in Mesoscopic Transport Devices with Two-Particle Interaction. Sci Rep 2015; 5:12873. [PMID: 26255858 PMCID: PMC4530461 DOI: 10.1038/srep12873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 07/10/2015] [Indexed: 12/02/2022] Open
Abstract
In this paper we demonstrate a new type of quantum phase coherence (QPC), which is generated by the two-body interaction. This conclusion is based on quantum master equation analysis for the full counting statistics of electron transport through two parallel quantum-dots with antiparallel magnetic fluxes in order to eliminate the Aharonov-Bohm interference of either single-particle or non-interacting two-particle wave functions. The interacting two-particle QPC is realized by the flux-dependent oscillation of the zero-frequency cumulants including the shot noise and skewness with a characteristic period. The accurately quantized peaks of cumulant spectrum may have technical applications to probe the two-body Coulomb interaction.
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164
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Kurpas M, Kędzierska B, Janus-Zygmunt I, Gorczyca-Goraj A, Wach E, Zipper E, Maśka MM. Charge transport through a semiconductor quantum dot-ring nanostructure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:265801. [PMID: 26052631 DOI: 10.1088/0953-8984/27/26/265801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Transport properties of a gated nanostructure depend crucially on the coupling of its states to the states of electrodes. In the case of a single quantum dot the coupling, for a given quantum state, is constant or can be slightly modified by additional gating. In this paper we consider a concentric dot-ring nanostructure (DRN) and show that its transport properties can be drastically modified due to the unique geometry. We calculate the dc current through a DRN in the Coulomb blockade regime and show that it can efficiently work as a single-electron transistor (SET) or a current rectifier. In both cases the transport characteristics strongly depend on the details of the confinement potential. The calculations are carried out for low and high bias regime, the latter being especially interesting in the context of current rectification due to fast relaxation processes.
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Affiliation(s)
- Marcin Kurpas
- Department of Theoretical Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
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165
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Fillipov S, Puttisong Y, Huang Y, Buyanova IA, Suraprapapich S, Tu CW, Chen WM. Exciton Fine-Structure Splitting in Self-Assembled Lateral InAs/GaAs Quantum-Dot Molecular Structures. ACS NANO 2015; 9:5741-5749. [PMID: 25965972 DOI: 10.1021/acsnano.5b01387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fine-structure splitting (FSS) of excitons in semiconductor nanostructures is a key parameter that has significant implications in photon entanglement and polarization conversion between electron spins and photons, relevant to quantum information technology and spintronics. Here, we investigate exciton FSS in self-organized lateral InAs/GaAs quantum-dot molecular structures (QMSs) including laterally aligned double quantum dots (DQDs), quantum-dot clusters (QCs), and quantum rings (QRs), by employing polarization-resolved microphotoluminescence (μPL) spectroscopy. We find a clear trend in FSS between the studied QMSs depending on their geometric arrangements, from a large FSS in the DQDs to a smaller FSS in the QCs and QRs. This trend is accompanied by a corresponding difference in the optical polarization directions of the excitons between these QMSs, namely, the bright-exciton lines are linearly polarized preferably along or perpendicular to the [11̅0] crystallographic axis in the DQDs that also defines the alignment direction of the two constituting QDs, whereas in the QCs and QRs, the polarization directions are randomly oriented. We attribute the observed trend in the FSS to a significant reduction of the asymmetry in the lateral confinement potential of the excitons in the QRs and QCs as compared with the DQDs, as a result of a compensation between the effects of lateral shape anisotropy and piezoelectric field. Our work demonstrates that FSS strongly depends on the geometric arrangements of the QMSs, which effectively tune the degree of the compensation effects and are capable of reducing FSS even in a strained QD system to a limit similar to strain-free QDs. This approach provides a pathway in obtaining high-symmetry quantum emitters desirable for realizing photon entanglement and spintronic devices based on such nanostructures, utilizing an uninterrupted epitaxial growth procedure without special requirements for lattice-matched materials combinations, specific substrate orientations, and nanolithography.
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Affiliation(s)
- Stanislav Fillipov
- †Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden
| | - Yuttapoom Puttisong
- †Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden
| | - Yuqing Huang
- †Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden
| | - Irina A Buyanova
- †Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden
| | - Suwaree Suraprapapich
- ‡Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, United States
| | - Charles W Tu
- ‡Department of Electrical and Computer Engineering, University of California, La Jolla, California 92093, United States
| | - Weimin M Chen
- †Department of Physics, Chemistry and Biology, Linköping University, Linköping S-581 83, Sweden
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166
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Srivastava A, Sidler M, Allain AV, Lembke DS, Kis A, Imamoğlu A. Optically active quantum dots in monolayer WSe2. NATURE NANOTECHNOLOGY 2015; 10:491-6. [PMID: 25938570 DOI: 10.1038/nnano.2015.60] [Citation(s) in RCA: 307] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/04/2015] [Indexed: 05/20/2023]
Abstract
Semiconductor quantum dots have emerged as promising candidates for the implementation of quantum information processing, because they allow for a quantum interface between stationary spin qubits and propagating single photons. In the meantime, transition-metal dichalcogenide monolayers have moved to the forefront of solid-state research due to their unique band structure featuring a large bandgap with degenerate valleys and non-zero Berry curvature. Here, we report the observation of zero-dimensional anharmonic quantum emitters, which we refer to as quantum dots, in monolayer tungsten diselenide, with an energy that is 20-100 meV lower than that of two-dimensional excitons. Photon antibunching in second-order photon correlations unequivocally demonstrates the zero-dimensional anharmonic nature of these quantum emitters. The strong anisotropic magnetic response of the spatially localized emission peaks strongly indicates that radiative recombination stems from localized excitons that inherit their electronic properties from the host transition-metal dichalcogenide. The large ∼1 meV zero-field splitting shows that the quantum dots have singlet ground states and an anisotropic confinement that is most probably induced by impurities or defects. The possibility of achieving electrical control in van der Waals heterostructures and to exploit the spin-valley degree of freedom renders transition-metal-dichalcogenide quantum dots interesting for quantum information processing.
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Affiliation(s)
- Ajit Srivastava
- Institute of Quantum Electronics, ETH Zurich, Zurich CH-8093, Switzerland
| | - Meinrad Sidler
- Institute of Quantum Electronics, ETH Zurich, Zurich CH-8093, Switzerland
| | - Adrien V Allain
- Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Switzerland
| | - Dominik S Lembke
- Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Switzerland
| | - Andras Kis
- Electrical Engineering Institute, Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Switzerland
| | - A Imamoğlu
- Institute of Quantum Electronics, ETH Zurich, Zurich CH-8093, Switzerland
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167
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Prance JR, Van Bael BJ, Simmons CB, Savage DE, Lagally MG, Friesen M, Coppersmith SN, Eriksson MA. Identifying single electron charge sensor events using wavelet edge detection. NANOTECHNOLOGY 2015; 26:215201. [PMID: 25930073 DOI: 10.1088/0957-4484/26/21/215201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The operation of solid-state qubits often relies on single-shot readout using a nanoelectronic charge sensor, and the detection of events in a noisy sensor signal is crucial for high fidelity readout of such qubits. The most common detection scheme, comparing the signal to a threshold value, is accurate at low noise levels but is not robust to low-frequency noise and signal drift. We describe an alternative method for identifying charge sensor events using wavelet edge detection. The technique is convenient to use and we show that, with realistic signals and a single tunable parameter, wavelet detection can outperform thresholding and is significantly more tolerant to 1/f and low-frequency noise.
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Affiliation(s)
- J R Prance
- University of Wisconsin-Madison, Wisconsin 53706, USA. Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK
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168
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Eng K, Ladd TD, Smith A, Borselli MG, Kiselev AA, Fong BH, Holabird KS, Hazard TM, Huang B, Deelman PW, Milosavljevic I, Schmitz AE, Ross RS, Gyure MF, Hunter AT. Isotopically enhanced triple-quantum-dot qubit. SCIENCE ADVANCES 2015; 1:e1500214. [PMID: 26601186 PMCID: PMC4640653 DOI: 10.1126/sciadv.1500214] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/09/2015] [Indexed: 05/05/2023]
Abstract
Like modern microprocessors today, future processors of quantum information may be implemented using all-electrical control of silicon-based devices. A semiconductor spin qubit may be controlled without the use of magnetic fields by using three electrons in three tunnel-coupled quantum dots. Triple dots have previously been implemented in GaAs, but this material suffers from intrinsic nuclear magnetic noise. Reduction of this noise is possible by fabricating devices using isotopically purified silicon. We demonstrate universal coherent control of a triple-quantum-dot qubit implemented in an isotopically enhanced Si/SiGe heterostructure. Composite pulses are used to implement spin-echo type sequences, and differential charge sensing enables single-shot state readout. These experiments demonstrate sufficient control with sufficiently low noise to enable the long pulse sequences required for exchange-only two-qubit logic and randomized benchmarking.
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169
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Muhonen JT, Laucht A, Simmons S, Dehollain JP, Kalra R, Hudson FE, Freer S, Itoh KM, Jamieson DN, McCallum JC, Dzurak AS, Morello A. Quantifying the quantum gate fidelity of single-atom spin qubits in silicon by randomized benchmarking. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:154205. [PMID: 25783435 DOI: 10.1088/0953-8984/27/15/154205] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Building upon the demonstration of coherent control and single-shot readout of the electron and nuclear spins of individual (31)P atoms in silicon, we present here a systematic experimental estimate of quantum gate fidelities using randomized benchmarking of 1-qubit gates in the Clifford group. We apply this analysis to the electron and the ionized (31)P nucleus of a single P donor in isotopically purified (28)Si. We find average gate fidelities of 99.95% for the electron and 99.99% for the nuclear spin. These values are above certain error correction thresholds and demonstrate the potential of donor-based quantum computing in silicon. By studying the influence of the shape and power of the control pulses, we find evidence that the present limitation to the gate fidelity is mostly related to the external hardware and not the intrinsic behaviour of the qubit.
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Affiliation(s)
- J T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, NSW 2052, Australia
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170
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Xue HB, Jiao HJ, Liang JQ, Liu WM. Non-Markovian full counting statistics in quantum dot molecules. Sci Rep 2015; 5:8978. [PMID: 25752245 PMCID: PMC4354005 DOI: 10.1038/srep08978] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/12/2015] [Indexed: 11/19/2022] Open
Abstract
Full counting statistics of electron transport is a powerful diagnostic tool for probing the nature of quantum transport beyond what is obtainable from the average current or conductance measurement alone. In particular, the non-Markovian dynamics of quantum dot molecule plays an important role in the nonequilibrium electron tunneling processes. It is thus necessary to understand the non-Markovian full counting statistics in a quantum dot molecule. Here we study the non-Markovian full counting statistics in two typical quantum dot molecules, namely, serially coupled and side-coupled double quantum dots with high quantum coherence in a certain parameter regime. We demonstrate that the non-Markovian effect manifests itself through the quantum coherence of the quantum dot molecule system, and has a significant impact on the full counting statistics in the high quantum-coherent quantum dot molecule system, which depends on the coupling of the quantum dot molecule system with the source and drain electrodes. The results indicated that the influence of the non-Markovian effect on the full counting statistics of electron transport, which should be considered in a high quantum-coherent quantum dot molecule system, can provide a better understanding of electron transport through quantum dot molecules.
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Affiliation(s)
- Hai-Bin Xue
- College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China
| | - Hu-Jun Jiao
- Department of Physics, Shanxi University, Taiyuan 030006, China
| | - Jiu-Qing Liang
- Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, China
| | - Wu-Ming Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
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171
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Scarlino P, Kawakami E, Stano P, Shafiei M, Reichl C, Wegscheider W, Vandersypen LMK. Spin-relaxation anisotropy in a GaAs quantum dot. PHYSICAL REVIEW LETTERS 2014; 113:256802. [PMID: 25554903 DOI: 10.1103/physrevlett.113.256802] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Indexed: 06/04/2023]
Abstract
We report that the electron spin-relaxation time T_{1} in a GaAs quantum dot with a spin-1/2 ground state has a 180° periodicity in the orientation of the in-plane magnetic field. This periodicity has been predicted for circular dots as being due to the interplay of Rashba and Dresselhaus spin orbit contributions. Different from this prediction, we find that the extrema in the T_{1} do not occur when the magnetic field is along the [110] and [11[over ¯]0] crystallographic directions. This deviation is attributed to an elliptical dot confining potential. The T_{1} varies by more than 1 order of magnitude when rotating a 3 T field, reaching about 80 ms for the optimal angle. We infer from the data that in our device the signs of the Rashba and Dresselhaus constants are opposite.
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Affiliation(s)
- P Scarlino
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - E Kawakami
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - P Stano
- RIKEN Center for Emergent Matter Science, Wako-shi, Saitama 351-0198, Japan and Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 84511 Bratislava, Slovakia
| | - M Shafiei
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
| | - C Reichl
- Solid State Physics Laboratory, ETH Zurich, Schafmattstrasse 16, 8093 Zurich, Switzerland
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zurich, Schafmattstrasse 16, 8093 Zurich, Switzerland
| | - L M K Vandersypen
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands
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172
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D'Anjou B, Coish WA. Soft decoding of a qubit readout apparatus. PHYSICAL REVIEW LETTERS 2014; 113:230402. [PMID: 25526105 DOI: 10.1103/physrevlett.113.230402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Indexed: 06/04/2023]
Abstract
Qubit readout is commonly performed by thresholding a collection of analog detector signals to obtain a sequence of single-shot bit values. The intrinsic irreversibility of the mapping from analog to digital signals discards soft information associated with an a posteriori confidence that can be assigned to each bit value when a detector is well characterized. Accounting for soft information, we show significant improvements in enhanced state detection with the quantum repetition code as well as quantum state or parameter estimation. These advantages persist in spite of non-Gaussian features of realistic readout models, experimentally relevant small numbers of qubits, and finite encoding errors. These results show useful and achievable advantages for a wide range of current experiments on quantum state tomography, parameter estimation, and qubit readout.
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Affiliation(s)
- B D'Anjou
- Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada
| | - W A Coish
- Department of Physics, McGill University, Montreal, Quebec H3A 2T8, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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173
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Veldhorst M, Hwang JCC, Yang CH, Leenstra AW, de Ronde B, Dehollain JP, Muhonen JT, Hudson FE, Itoh KM, Morello A, Dzurak AS. An addressable quantum dot qubit with fault-tolerant control-fidelity. NATURE NANOTECHNOLOGY 2014; 9:981-985. [PMID: 25305743 DOI: 10.1038/nnano.2014.216] [Citation(s) in RCA: 202] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 08/28/2014] [Indexed: 06/04/2023]
Abstract
Exciting progress towards spin-based quantum computing has recently been made with qubits realized using nitrogen-vacancy centres in diamond and phosphorus atoms in silicon. For example, long coherence times were made possible by the presence of spin-free isotopes of carbon and silicon. However, despite promising single-atom nanotechnologies, there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered, but strong coupling to noise has severely limited their dephasing times and control fidelities. Here, we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford-based randomized benchmarking and consistent with that required for fault-tolerant quantum computing. This qubit has dephasing time T2* = 120 μs and coherence time T2 = 28 ms, both orders of magnitude larger than in other types of semiconductor qubit. By gate-voltage-tuning the electron g*-factor we can Stark shift the electron spin resonance frequency by more than 3,000 times the 2.4 kHz electron spin resonance linewidth, providing a direct route to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies.
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Affiliation(s)
- M Veldhorst
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J C C Hwang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - C H Yang
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - A W Leenstra
- University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - B de Ronde
- University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - J P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - F E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - K M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - A Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
| | - A S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, The University of New South Wales, Sydney, New South Wales 2052, Australia
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174
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Kawakami E, Scarlino P, Ward DR, Braakman FR, Savage DE, Lagally MG, Friesen M, Coppersmith SN, Eriksson MA, Vandersypen LMK. Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot. NATURE NANOTECHNOLOGY 2014; 9:666-670. [PMID: 25108810 DOI: 10.1038/nnano.2014.153] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/27/2014] [Indexed: 06/03/2023]
Abstract
Nanofabricated quantum bits permit large-scale integration but usually suffer from short coherence times due to interactions with their solid-state environment. The outstanding challenge is to engineer the environment so that it minimally affects the qubit, but still allows qubit control and scalability. Here, we demonstrate a long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control. The spin is driven by resonant microwave electric fields in a transverse magnetic field gradient from a local micromagnet, and the spin state is read out in the single-shot mode. Electron spin resonance occurs at two closely spaced frequencies, which we attribute to two valley states. Thanks to the weak hyperfine coupling in silicon, a Ramsey decay timescale of 1 μs is observed, almost two orders of magnitude longer than the intrinsic timescales in GaAs quantum dots, whereas gate operation times are comparable to those reported in GaAs. The spin echo decay time is ~40 μs, both with one and four echo pulses, possibly limited by intervalley scattering. These advances strongly improve the prospects for quantum information processing based on quantum dots.
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Affiliation(s)
- E Kawakami
- 1] Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands [2]
| | - P Scarlino
- 1] Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands [2]
| | - D R Ward
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - F R Braakman
- 1] Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands [2]
| | - D E Savage
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M G Lagally
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Mark Friesen
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S N Coppersmith
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M A Eriksson
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - L M K Vandersypen
- Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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175
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Pawłowski J, Szumniak P, Skubis A, Bednarek S. Electron spin separation without magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:345302. [PMID: 25106038 DOI: 10.1088/0953-8984/26/34/345302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A nanodevice capable of separating spins of two electrons confined in a quantum dot formed in a gated semiconductor nanowire is proposed. Two electrons confined initially in a single quantum dot in the singlet state are transformed into the system of two electrons confined in two spatially separated quantum dots with opposite spins. In order to separate the electrons' spins we exploit transitions between the singlet and the triplet state, which are induced by resonantly oscillating Rashba spin-orbit coupling strength. The proposed device is all electrically controlled and the electron spin separation can be realized within tens of picoseconds. The results are supported by solving numerically the quasi-one-dimensional time-dependent Schroedinger equation for two electrons, where the electron-electron correlations are taken into account in the exact manner.
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Affiliation(s)
- J Pawłowski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Kraków, Poland
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176
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Kim D, Shi Z, Simmons CB, Ward DR, Prance JR, Koh TS, Gamble JK, Savage DE, Lagally MG, Friesen M, Coppersmith SN, Eriksson MA. Quantum control and process tomography of a semiconductor quantum dot hybrid qubit. Nature 2014; 511:70-4. [DOI: 10.1038/nature13407] [Citation(s) in RCA: 217] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/28/2014] [Indexed: 11/09/2022]
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177
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Thiele S, Balestro F, Ballou R, Klyatskaya S, Ruben M, Wernsdorfer W. Electrically driven nuclear spin resonance in single-molecule magnets. Science 2014; 344:1135-8. [PMID: 24904159 DOI: 10.1126/science.1249802] [Citation(s) in RCA: 490] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent advances in addressing isolated nuclear spins have opened up a path toward using nuclear-spin-based quantum bits. Local magnetic fields are normally used to coherently manipulate the state of the nuclear spin; however, electrical manipulation would allow for fast switching and spatially confined spin control. Here, we propose and demonstrate coherent single nuclear spin manipulation using electric fields only. Because there is no direct coupling between the spin and the electric field, we make use of the hyperfine Stark effect as a magnetic field transducer at the atomic level. This quantum-mechanical process is present in all nuclear spin systems, such as phosphorus or bismuth atoms in silicon, and offers a general route toward the electrical control of nuclear-spin-based devices.
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Affiliation(s)
- Stefan Thiele
- CNRS, Inst NEEL, F-38042 Grenoble, France. Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
| | - Franck Balestro
- CNRS, Inst NEEL, F-38042 Grenoble, France. Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France. Institut Universitaire de France, 103 boulevard Saint-Michel, 75005 Paris, France
| | - Rafik Ballou
- CNRS, Inst NEEL, F-38042 Grenoble, France. Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France
| | - Svetlana Klyatskaya
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Mario Ruben
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany. Institut de Physique et de Chimie des Materiaux de Strasbourg, CNRS, 67034 Strasbourg, France
| | - Wolfgang Wernsdorfer
- CNRS, Inst NEEL, F-38042 Grenoble, France. Université Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France.
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178
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Dehollain JP, Muhonen JT, Tan KY, Saraiva A, Jamieson DN, Dzurak AS, Morello A. Single-shot readout and relaxation of singlet and triplet states in exchange-coupled 31P electron spins in silicon. PHYSICAL REVIEW LETTERS 2014; 112:236801. [PMID: 24972221 DOI: 10.1103/physrevlett.112.236801] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Indexed: 06/03/2023]
Abstract
We present the experimental observation of a large exchange coupling J ≈ 300 μeV between two (31)P electron spin qubits in silicon. The singlet and triplet states of the coupled spins are monitored in real time by a single-electron transistor, which detects ionization from tunnel-rate-dependent processes in the coupled spin system, yielding single-shot readout fidelities above 95%. The triplet to singlet relaxation time T(1) ≈ 4 ms at zero magnetic field agrees with the theoretical prediction for J-coupled 31P dimers in silicon. The time evolution of the two-electron state populations gives further insight into the valley-orbit eigenstates of the donor dimer, valley selection rules and relaxation rates, and the role of hyperfine interactions. These results pave the way to the realization of two-qubit quantum logic gates with spins in silicon and highlight the necessity to adopt gating schemes compatible with weak J-coupling strengths.
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Affiliation(s)
- Juan P Dehollain
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Juha T Muhonen
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Kuan Y Tan
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Andre Saraiva
- Instituto de Fisica, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, Brazil and University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - David N Jamieson
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Andrew S Dzurak
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Andrea Morello
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
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179
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Korkusinski M, Hawrylak P. Quantum strain sensor with a topological insulator HgTe quantum dot. Sci Rep 2014; 4:4903. [PMID: 24811674 PMCID: PMC4014981 DOI: 10.1038/srep04903] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 04/10/2014] [Indexed: 11/21/2022] Open
Abstract
We present a theory of electronic properties of HgTe quantum dot and propose a strain sensor based on a strain-driven transition from a HgTe quantum dot with inverted bandstructure and robust topologically protected quantum edge states to a normal state without edge states in the energy gap. The presence or absence of edge states leads to large on/off ratio of conductivity across the quantum dot, tunable by adjusting the number of conduction channels in the source-drain voltage window. The electronic properties of a HgTe quantum dot as a function of size and applied strain are described using eight-band k · p Luttinger and Bir-Pikus Hamiltonians, with surface states identified with chirality of Luttinger spinors and obtained through extensive numerical diagonalization of the Hamiltonian.
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Affiliation(s)
- Marek Korkusinski
- Quantum Theory Group, Security and Disruptive Technologies Portfolio, Emerging Technologies Division, National Research Council, Ottawa, Canada K1A 0R6
| | - Pawel Hawrylak
- Quantum Theory Group, Security and Disruptive Technologies Portfolio, Emerging Technologies Division, National Research Council, Ottawa, Canada K1A 0R6
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180
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Delteil A, Gao WB, Fallahi P, Miguel-Sanchez J, Imamoğlu A. Observation of quantum jumps of a single quantum dot spin using submicrosecond single-shot optical readout. PHYSICAL REVIEW LETTERS 2014; 112:116802. [PMID: 24702401 DOI: 10.1103/physrevlett.112.116802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Indexed: 06/03/2023]
Abstract
Single-shot readout of individual qubits is typically the slowest process among the elementary single- and two-qubit operations required for quantum information processing. Here, we use resonance fluorescence from a single-electron charged quantum dot to read out the spin-qubit state in 800 nanoseconds with a fidelity exceeding 80%. Observation of the spin evolution on longer time scales reveals quantum jumps of the spin state: we use the experimentally determined waiting-time distribution to characterize the quantum jumps.
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Affiliation(s)
- Aymeric Delteil
- Institute of Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Wei-Bo Gao
- Institute of Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Parisa Fallahi
- Institute of Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
| | | | - Atac Imamoğlu
- Institute of Quantum Electronics, ETH Zurich, CH-8093 Zurich, Switzerland
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181
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Few-Qubit Magnetic Resonance Quantum Information Processors: Simulating Chemistry and Physics. ADVANCES IN CHEMICAL PHYSICS 2014. [DOI: 10.1002/9781118742631.ch08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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182
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Dolde F, Doherty MW, Michl J, Jakobi I, Naydenov B, Pezzagna S, Meijer J, Neumann P, Jelezko F, Manson NB, Wrachtrup J. Nanoscale detection of a single fundamental charge in ambient conditions using the NV- center in diamond. PHYSICAL REVIEW LETTERS 2014; 112:097603. [PMID: 24655277 DOI: 10.1103/physrevlett.112.097603] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Indexed: 06/03/2023]
Abstract
Single charge nanoscale detection in ambient conditions is a current frontier in metrology that has diverse interdisciplinary applications. Here, such single charge detection is demonstrated using two nitrogen-vacancy (NV) centers in diamond. One NV center is employed as a sensitive electrometer to detect the change in electric field created by the displacement of a single electron resulting from the optical switching of the other NV center between its neutral (NV(0)) and negative (NV(-)) charge states. As a consequence, our measurements also provide direct insight into the charge dynamics inside the material.
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Affiliation(s)
- Florian Dolde
- 3. Physikalisches Institut, Research Center SCoPE and IQST, Universität Stuttgart, Pfaffenwaldring 57. D-70550 Stuttgart, Germany
| | - Marcus W Doherty
- Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Australian Capital Territory 0200, Australia
| | - Julia Michl
- 3. Physikalisches Institut, Research Center SCoPE and IQST, Universität Stuttgart, Pfaffenwaldring 57. D-70550 Stuttgart, Germany
| | - Ingmar Jakobi
- 3. Physikalisches Institut, Research Center SCoPE and IQST, Universität Stuttgart, Pfaffenwaldring 57. D-70550 Stuttgart, Germany
| | - Boris Naydenov
- Institut für Quantenoptik and IQST, Universität Ulm, Ulm D-89073, Germany
| | | | - Jan Meijer
- Physikalisches Institut, Universität Leipzig, 04103 Leipzig, Germany
| | - Philipp Neumann
- 3. Physikalisches Institut, Research Center SCoPE and IQST, Universität Stuttgart, Pfaffenwaldring 57. D-70550 Stuttgart, Germany
| | - Fedor Jelezko
- Institut für Quantenoptik and IQST, Universität Ulm, Ulm D-89073, Germany
| | - Neil B Manson
- Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Australian Capital Territory 0200, Australia
| | - Jörg Wrachtrup
- 3. Physikalisches Institut, Research Center SCoPE and IQST, Universität Stuttgart, Pfaffenwaldring 57. D-70550 Stuttgart, Germany
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183
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Xue HB. Full counting statistics as a probe of quantum coherence in a side-coupled double quantum dot system. ANNALS OF PHYSICS 2013; 339:208-217. [DOI: 10.1016/j.aop.2013.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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184
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Abstract
We discuss graphene nanoribbon-based charge sensors and focus on their functionality in the presence of external magnetic fields and high frequency pulses applied to a nearby gate electrode. The charge detectors work well with in-plane magnetic fields of up to 7 T and pulse frequencies of up to 20 MHz. By analyzing the step height in the charge detector's current at individual charging events in a nearby quantum dot, we determine the ideal operation conditions with respect to the applied charge detector bias. Average charge sensitivities of 1.3 × 10(-3)e Hz(-1/2) can be achieved. Additionally, we investigate the back action of the charge detector current on the quantum transport through a nearby quantum dot. By varying the charge detector bias from 0 to 4.5 mV, we can increase the Coulomb peak currents measured at the quantum dot by a factor of around 400. Furthermore, we can completely lift the Coulomb blockade in the quantum dot.
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Affiliation(s)
- C Neumann
- JARA-FIT and II Institute of Physics B, RWTH Aachen University, D-52074 Aachen, Germany. Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich, D-52425 Jülich, Germany
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185
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Khaetskii A, Golovach VN, Hu X, Zutić I. Proposal for a phonon laser utilizing quantum-dot spin states. PHYSICAL REVIEW LETTERS 2013; 111:186601. [PMID: 24237544 DOI: 10.1103/physrevlett.111.186601] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/29/2013] [Indexed: 06/02/2023]
Abstract
We propose a nanoscale realization of a phonon laser utilizing phonon-assisted spin flips in quantum dots to amplify sound. Owing to a long spin relaxation time, the device can be operated in a strong pumping regime, in which the population inversion is close to its maximal value allowed under Fermi statistics. In this regime, the threshold for stimulated emission is unaffected by spontaneous spin flips. Considering a nanowire with quantum dots defined along its length, we show that a further improvement arises from confining the phonons to one dimension, and thus reducing the number of phonon modes available for spontaneous emission. Our work calls for the development of nanowire-based, high-finesse phonon resonators.
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Affiliation(s)
- A Khaetskii
- Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260-1500
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186
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Klein K, Hauer B, Stoib B, Trautwein M, Matich S, Huebl H, Astakhov O, Finger F, Bittl R, Stutzmann M, Brandt MS. The electrically detected magnetic resonance microscope: combining conductive atomic force microscopy with electrically detected magnetic resonance. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2013; 84:103911. [PMID: 24182133 DOI: 10.1063/1.4827036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present the design and implementation of a scanning probe microscope, which combines electrically detected magnetic resonance (EDMR) and (photo-)conductive atomic force microscopy ((p)cAFM). The integration of a 3-loop 2-gap X-band microwave resonator into an AFM allows the use of conductive AFM tips as a movable contact for EDMR experiments. The optical readout of the AFM cantilever is based on an infrared laser to avoid disturbances of current measurements by absorption of straylight of the detection laser. Using amorphous silicon thin film samples with varying defect densities, the capability to detect a spatial EDMR contrast is demonstrated. Resonant current changes as low as 20 fA can be detected, allowing the method to realize a spin sensitivity of 8×10(6)spins/√Hz at room temperature.
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Affiliation(s)
- Konrad Klein
- Walter Schottky Institut, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany
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187
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De Greve K, Press D, McMahon PL, Yamamoto Y. Ultrafast optical control of individual quantum dot spin qubits. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2013; 76:092501. [PMID: 24006335 DOI: 10.1088/0034-4885/76/9/092501] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Single spins in semiconductor quantum dots form a promising platform for solid-state quantum information processing. The spin-up and spin-down states of a single electron or hole, trapped inside a quantum dot, can represent a single qubit with a reasonably long decoherence time. The spin qubit can be optically coupled to excited (charged exciton) states that are also trapped in the quantum dot, which provides a mechanism to quickly initialize, manipulate and measure the spin state with optical pulses, and to interface between a stationary matter qubit and a 'flying' photonic qubit for quantum communication and distributed quantum information processing. The interaction of the spin qubit with light may be enhanced by placing the quantum dot inside a monolithic microcavity. An entire system, consisting of a two-dimensional array of quantum dots and a planar microcavity, may plausibly be constructed by modern semiconductor nano-fabrication technology and could offer a path toward chip-sized scalable quantum repeaters and quantum computers. This article reviews the recent experimental developments in optical control of single quantum dot spins for quantum information processing. We highlight demonstrations of a complete set of all-optical single-qubit operations on a single quantum dot spin: initialization, an arbitrary SU(2) gate, and measurement. We review the decoherence and dephasing mechanisms due to hyperfine interaction with the nuclear-spin bath, and show how the single-qubit operations can be combined to perform spin echo sequences that extend the qubit decoherence from a few nanoseconds to several microseconds, more than 5 orders of magnitude longer than the single-qubit gate time. Two-qubit coupling is discussed, both within a single chip by means of exchange coupling of nearby spins and optically induced geometric phases, as well as over longer-distances. Long-distance spin-spin entanglement can be generated if each spin can emit a photon that is entangled with the spin, and these photons are then interfered. We review recent work demonstrating entanglement between a stationary spin qubit and a flying photonic qubit. These experiments utilize the polarization- and frequency-dependent spontaneous emission from the lowest charged exciton state to single spin Zeeman sublevels.
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188
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Leijnse M, Flensberg K. Coupling spin qubits via superconductors. PHYSICAL REVIEW LETTERS 2013; 111:060501. [PMID: 23971543 DOI: 10.1103/physrevlett.111.060501] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Indexed: 06/02/2023]
Abstract
We show how superconductors can be used to couple, initialize, and read out spatially separated spin qubits. When two single-electron quantum dots are tunnel coupled to the same superconductor, the singlet component of the two-electron state partially leaks into the superconductor via crossed Andreev reflection. This induces a gate-controlled singlet-triplet splitting which, with an appropriate superconductor geometry, remains large for dot separations within the superconducting coherence length. Furthermore, we show that when two double-dot singlet-triplet qubits are tunnel coupled to a superconductor with finite charging energy, crossed Andreev reflection enables a strong two-qubit coupling over distances much larger than the coherence length.
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Affiliation(s)
- Martin Leijnse
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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189
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Wei HR, Deng FG. Scalable photonic quantum computing assisted by quantum-dot spin in double-sided optical microcavity. OPTICS EXPRESS 2013; 21:17671-17685. [PMID: 23938640 DOI: 10.1364/oe.21.017671] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We investigate the possibility of achieving scalable photonic quantum computing by the giant optical circular birefringence induced by a quantum-dot spin in a double-sided optical microcavity as a result of cavity quantum electrodynamics. We construct a deterministic controlled-not gate on two photonic qubits by two single-photon input-output processes and the readout on an electron-medium spin confined in an optical resonant microcavity. This idea could be applied to multi-qubit gates on photonic qubits and we give the quantum circuit for a three-photon Toffoli gate. High fidelities and high efficiencies could be achieved when the side leakage to the cavity loss rate is low. It is worth pointing out that our devices work in both the strong and the weak coupling regimes.
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Affiliation(s)
- Hai-Rui Wei
- Department of Physics, Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China
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190
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Thiele S, Vincent R, Holzmann M, Klyatskaya S, Ruben M, Balestro F, Wernsdorfer W. Electrical readout of individual nuclear spin trajectories in a single-molecule magnet spin transistor. PHYSICAL REVIEW LETTERS 2013; 111:037203. [PMID: 23909356 DOI: 10.1103/physrevlett.111.037203] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Indexed: 06/02/2023]
Abstract
We present the electrical readout of time trajectories obtained from an isolated nuclear spin. The device, a TbPc(2) single-molecule magnet spin transistor, detects the four different nuclear spin states of the Tb(3+) ion with fidelities better than 69%, allowing us to measure individual relaxation times (T(1)) of several tens of seconds. A good agreement with quantum Monte Carlo simulations suggests that the relaxation times are limited by the current tunneling through the transistor, which opens up the possibility to tune T(1) electrically by means of bias and gate voltages.
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Affiliation(s)
- S Thiele
- Institut Néel, CNRS and Université Joseph Fourier, B.P. 166, 38042 Grenoble Cedex 09, France
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191
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Fujita T, Kiyama H, Morimoto K, Teraoka S, Allison G, Ludwig A, Wieck AD, Oiwa A, Tarucha S. Nondestructive real-time measurement of charge and spin dynamics of photoelectrons in a double quantum dot. PHYSICAL REVIEW LETTERS 2013; 110:266803. [PMID: 23848908 DOI: 10.1103/physrevlett.110.266803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Indexed: 06/02/2023]
Abstract
We demonstrate one and two photoelectron trapping and the subsequent dynamics associated with interdot transfer in double quantum dots over a time scale much shorter than the typical spin lifetime. Identification of photoelectron trapping is achieved via resonant interdot tunneling of the photoelectrons in the excited states. The interdot transfer enables detection of single photoelectrons in a nondestructive manner. When two photoelectrons are trapped at almost the same time we observed that the interdot resonant tunneling is strongly affected by the Coulomb interaction between the electrons. Finally the influence of the two-electron singlet-triplet state hybridization has been detected using the interdot tunneling of a photoelectron.
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Affiliation(s)
- T Fujita
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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192
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Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting. Nat Commun 2013; 4:2069. [DOI: 10.1038/ncomms3069] [Citation(s) in RCA: 193] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [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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193
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Büch H, Mahapatra S, Rahman R, Morello A, Simmons MY. Spin readout and addressability of phosphorus-donor clusters in silicon. Nat Commun 2013; 4:2017. [DOI: 10.1038/ncomms3017] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 05/16/2013] [Indexed: 11/09/2022] Open
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194
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Ribeiro H, Burkard G. Nuclear spins keep coming back. NATURE MATERIALS 2013; 12:469-471. [PMID: 23695732 DOI: 10.1038/nmat3671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- Hugo Ribeiro
- Department of Physics, University of Basel, Basel, Switzerland.
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195
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Rossier JF. Single-atom devices: Quantum engineering. NATURE MATERIALS 2013; 12:480-481. [PMID: 23695744 DOI: 10.1038/nmat3670] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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196
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Srinivasa V, Nowack KC, Shafiei M, Vandersypen LMK, Taylor JM. Simultaneous spin-charge relaxation in double quantum dots. PHYSICAL REVIEW LETTERS 2013; 110:196803. [PMID: 23705734 DOI: 10.1103/physrevlett.110.196803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Indexed: 06/02/2023]
Abstract
We investigate phonon-induced spin and charge relaxation mediated by spin-orbit and hyperfine interactions for a single electron confined within a double quantum dot. A simple toy model incorporating both direct decay to the ground state of the double dot and indirect decay via an intermediate excited state yields an electron spin relaxation rate that varies nonmonotonically with the detuning between the dots. We confirm this model with experiments performed on a GaAs double dot, demonstrating that the relaxation rate exhibits the expected detuning dependence and can be electrically tuned over several orders of magnitude. Our analysis suggests that spin-orbit mediated relaxation via phonons serves as the dominant mechanism through which the double-dot electron spin-flip rate varies with detuning.
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Affiliation(s)
- V Srinivasa
- Joint Quantum Institute, University of Maryland, College Park, Maryland 20742, USA.
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197
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White AJ, Migliore A, Galperin M, Nitzan A. Quantum transport with two interacting conduction channels. J Chem Phys 2013; 138:174111. [PMID: 23656118 DOI: 10.1063/1.4802587] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The transport properties of a conduction junction model characterized by two mutually coupled channels that strongly differ in their couplings to the leads are investigated. Models of this type describe molecular redox junctions (where a level that is weakly coupled to the leads controls the molecular charge, while a strongly coupled one dominates the molecular conduction), and electron counting devices in which the current in a point contact is sensitive to the charging state of a nearby quantum dot. Here we consider the case where transport in the strongly coupled channel has to be described quantum mechanically (covering the full range between sequential tunneling and co-tunneling), while conduction through the weakly coupled channel is a sequential process that could by itself be described by a simple master equation. We compare the result of a full quantum calculation based on the pseudoparticle non-equilibrium Green function method to that obtained from an approximate mixed quantum-classical calculation, where correlations between the channels are taken into account through either the averaged rates or the averaged energy. We find, for the steady state current, that the approximation based on the averaged rates works well in most of the voltage regime, with marked deviations from the full quantum results only at the threshold for charging the weekly coupled level. These deviations are important for accurate description of the negative differential conduction behavior that often characterizes redox molecular junctions in the neighborhood of this threshold.
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Affiliation(s)
- Alexander J White
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
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198
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Goker A, Gedik E. Temporal evolution of the Seebeck coefficient in an ac driven strongly correlated quantum dot. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:125301. [PMID: 23420337 DOI: 10.1088/0953-8984/25/12/125301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study the response of the thermopower of a quantum dot in the Kondo regime to sinusoidal displacement of the dot energy level via a gate voltage using time dependent non-crossing approximation and linear response Onsager relations. Instantaneous thermopower begins to exhibit complex fluctuations when the driving amplitude is increased at constant driving frequency. We also find that the time averaged thermopower decreases steadily until it saturates at constant driving amplitude as a function of inverse driving frequency. On the other hand, time averaged thermopower is found to be quite sensitive to ambient temperature at all driving frequencies for large driving amplitudes. We discuss the underlying microscopic mechanism for these peculiarities based on the behaviour of the dot density of states.
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Affiliation(s)
- A Goker
- Department of Physics, Bilecik University, Gülümbe, Bilecik, Turkey.
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199
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Shafiei M, Nowack KC, Reichl C, Wegscheider W, Vandersypen LMK. Resolving spin-orbit- and hyperfine-mediated electric dipole spin resonance in a quantum dot. PHYSICAL REVIEW LETTERS 2013; 110:107601. [PMID: 23521296 DOI: 10.1103/physrevlett.110.107601] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Indexed: 06/01/2023]
Abstract
We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert the electron spin, we observe an unusually wide and asymmetric response as a function of the magnetic field. Simulations support the interpretation of the line shape in terms of four different resonance conditions. These findings may lead to isotope-selective control of dynamic nuclear polarization in quantum dots.
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Affiliation(s)
- M Shafiei
- Kavli Institute of Nanoscience, Delft University of Technology, PO Box 5046, 2600 GA Delft, The Netherlands.
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200
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Colless JI, Mahoney AC, Hornibrook JM, Doherty AC, Lu H, Gossard AC, Reilly DJ. Dispersive readout of a few-electron double quantum dot with fast RF gate sensors. PHYSICAL REVIEW LETTERS 2013; 110:046805. [PMID: 25166190 DOI: 10.1103/physrevlett.110.046805] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Indexed: 06/03/2023]
Abstract
We report the dispersive charge-state readout of a double quantum dot in the few-electron regime using the in situ gate electrodes as sensitive detectors. We benchmark this gate sensing technique against the well established quantum point contact charge detector and find comparable performance with a bandwidth of ∼ 10 MHz and an equivalent charge sensitivity of ∼ 6.3 × 10(-3) e/sqrt[Hz]. Dispersive gate sensing alleviates the burden of separate charge detectors for quantum dot systems and promises to enable readout of qubits in scaled-up arrays.
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Affiliation(s)
- J I Colless
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - A C Mahoney
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - J M Hornibrook
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - A C Doherty
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - H Lu
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - A C Gossard
- Materials Department, University of California, Santa Barbara, California 93106, USA
| | - D J Reilly
- ARC Centre of Excellence for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
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