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Connors EJ, Nelson J, Edge LF, Nichol JM. Charge-noise spectroscopy of Si/SiGe quantum dots via dynamically-decoupled exchange oscillations. Nat Commun 2022; 13:940. [PMID: 35177606 PMCID: PMC8854405 DOI: 10.1038/s41467-022-28519-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 01/26/2022] [Indexed: 11/23/2022] Open
Abstract
Electron spins in silicon quantum dots are promising qubits due to their long coherence times, scalable fabrication, and potential for all-electrical control. However, charge noise in the host semiconductor presents a major obstacle to achieving high-fidelity single- and two-qubit gates in these devices. In this work, we measure the charge-noise spectrum of a Si/SiGe singlet-triplet qubit over nearly 12 decades in frequency using a combination of methods, including dynamically-decoupled exchange oscillations with up to 512 π pulses during the qubit evolution. The charge noise is colored across the entire frequency range of our measurements, although the spectral exponent changes with frequency. Moreover, the charge-noise spectrum inferred from conductance measurements of a proximal sensor quantum dot agrees with that inferred from coherent oscillations of the singlet-triplet qubit, suggesting that simple transport measurements can accurately characterize the charge noise over a wide frequency range in Si/SiGe quantum dots.
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Affiliation(s)
- Elliot J Connors
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, 14627, USA
| | - J Nelson
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, 14627, USA
| | - Lisa F Edge
- HRL Laboratories LLC, 3011 Malibu Canyon Road, Malibu, CA, 90265, USA
| | - John M Nichol
- Department of Physics and Astronomy, University of Rochester, Rochester, NY, 14627, USA.
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2
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Kulkarni A, Bindal N, Kaushik BK. Quantum Computing Circuits Based on Spin-Torque Qubit Architecture: Toward the Physical Realization of Quantum Computers. IEEE NANOTECHNOLOGY MAGAZINE 2019. [DOI: 10.1109/mnano.2019.2927782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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3
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Probing and driving of spin and charge states in double quantum dot under the quench. Sci Rep 2019; 9:3130. [PMID: 30816339 PMCID: PMC6395824 DOI: 10.1038/s41598-019-40038-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 02/07/2019] [Indexed: 11/14/2022] Open
Abstract
We have analyzed theoretically quenched dynamics of correlated double quantum dot (DQD) due to the switching “on” and “off” coupling to reservoirs. The possibility for controllable manipulation of charge and spin states in the double quantum dot was revealed and discussed. The proposed experimental scheme allows to prepare in DQD maximally entangled pure triplet state and to drive it to another entangled singlet state by tuning both applied bias and gate voltage. It was also demonstrated that the symmetry properties of the total system (double quantum dot coupled to electron reservoirs) allow to resolve the initially prepared two-electron states by detecting non-stationary spin-polarized currents flowing in both reservoirs and controlling the residual charge.
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4
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Russ M, Petta JR, Burkard G. Quadrupolar Exchange-Only Spin Qubit. PHYSICAL REVIEW LETTERS 2018; 121:177701. [PMID: 30411952 DOI: 10.1103/physrevlett.121.177701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Indexed: 06/08/2023]
Abstract
We propose a quadrupolar exchange-only spin qubit that is highly robust against charge noise and nuclear spin dephasing, the dominant decoherence mechanisms in quantum dots. The qubit consists of four electrons trapped in three quantum dots, and operates in a decoherence-free subspace to mitigate dephasing due to nuclear spins. To reduce sensitivity to charge noise, the qubit can be completely operated at an extended charge noise sweet spot that is first-order insensitive to electrical fluctuations. Because of on-site exchange mediated by the Coulomb interaction, the qubit energy splitting is electrically controllable and can amount to several GHz even in the "off" configuration, making it compatible with conventional microwave cavities.
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Affiliation(s)
- Maximilian Russ
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
| | - J R Petta
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Guido Burkard
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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5
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Łuczak J, Bułka BR. Two-qubit logical operations in three quantum dots system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:225601. [PMID: 29658887 DOI: 10.1088/1361-648x/aabe50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We consider a model of two interacting always-on, exchange-only qubits for which controlled phase (CPHASE), controlled NOT (CNOT), quantum Fourier transform (QFT) and SWAP operations can be implemented only in a few electrical pulses in a nanosecond time scale. Each qubit is built of three quantum dots (TQD) in a triangular geometry with three electron spins which are always kept coupled by exchange interactions only. The qubit states are encoded in a doublet subspace and are fully electrically controlled by a voltage applied to gate electrodes. The two qubit quantum gates are realized by short electrical pulses which change the triangular symmetry of TQD and switch on exchange interaction between the qubits. We found an optimal configuration to implement the CPHASE gate by a single pulse of the order 2.3 ns. Using this gate, in combination with single qubit operations, we searched for optimal conditions to perform the other gates: CNOT, QFT and SWAP. Our studies take into account environment effects and leakage processes as well. The results suggest that the system can be implemented for fault tolerant quantum computations.
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Affiliation(s)
- Jakub Łuczak
- Institute of Molecular Physics, Polish Academy of Sciences, ul. M. Smoluchowskiego 17, 60-179 Poznań, Poland
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6
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Laucht A, Kalra R, Simmons S, Dehollain JP, Muhonen JT, Mohiyaddin FA, Freer S, Hudson FE, Itoh KM, Jamieson DN, McCallum JC, Dzurak AS, Morello A. A dressed spin qubit in silicon. NATURE NANOTECHNOLOGY 2017; 12:61-66. [PMID: 27749833 DOI: 10.1038/nnano.2016.178] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 08/17/2016] [Indexed: 06/06/2023]
Abstract
Coherent dressing of a quantum two-level system provides access to a new quantum system with improved properties-a different and easily tunable level splitting, faster control and longer coherence times. In our work we investigate the properties of the dressed, donor-bound electron spin in silicon, and assess its potential as a quantum bit in scalable architectures. The two dressed spin-polariton levels constitute a quantum bit that can be coherently driven with an oscillating magnetic field, an oscillating electric field, frequency modulation of the driving field or a simple detuning pulse. We measure coherence times of and , one order of magnitude longer than those of the undressed spin. Furthermore, the use of the dressed states enables coherent coupling of the solid-state spins to electric fields and mechanical oscillations.
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Affiliation(s)
- Arne Laucht
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Rachpon Kalra
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Stephanie Simmons
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - 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
| | - Fahd A Mohiyaddin
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Solomon Freer
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Fay E Hudson
- Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia
| | - Kohei M Itoh
- School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kanagawa 223-8522, Japan
| | - David N Jamieson
- Centre for Quantum Computation and Communication Technology, School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Jeffrey C McCallum
- 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
| | - A 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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7
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Noise filtering of composite pulses for singlet-triplet qubits. Sci Rep 2016; 6:28996. [PMID: 27383129 PMCID: PMC4935950 DOI: 10.1038/srep28996] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/13/2016] [Indexed: 11/18/2022] Open
Abstract
Semiconductor quantum dot spin qubits are promising candidates for quantum computing. In these systems, the dynamically corrected gates offer considerable reduction of gate errors and are therefore of great interest both theoretically and experimentally. They are, however, designed under the static-noise model and may be considered as low-frequency filters. In this work, we perform a comprehensive theoretical study of the response of a type of dynamically corrected gates, namely the supcode for singlet-triplet qubits, to realistic 1/f noises with frequency spectra 1/ωα. Through randomized benchmarking, we have found that supcode offers improvement of the gate fidelity for α 1 and the improvement becomes exponentially more pronounced with the increase of the noise exponent in the range 1 α ≤ 3 studied. On the other hand, for small α, supcode will not offer any improvement. The δJ-supcode, specifically designed for systems where the nuclear noise is absent, is found to offer additional error reduction than the full supcode for charge noises. The computed filter transfer functions of the supcode gates are also presented.
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8
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Xue N, Xie H, Wang Z, Liang JQ. Spin-polarization inversion of transport current and tunnel magnetoresistance through a non-collinear uniaxial-molecule-magnet dimer junction with electrode magnetization. RSC Adv 2016. [DOI: 10.1039/c6ra03515a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this paper, we study quantum transport through a tunnel junction embedded with a non-collinear uniaxial molecule-magnet-dimer with the magnetization of ferromagnetic electrodes.
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Affiliation(s)
- Naitao Xue
- Institute of Theoretical Physics and Department of Physics
- Shanxi University
- China
| | - Haiqing Xie
- Department of Physics
- Taiyuan Normal University
- China
| | - Zhimei Wang
- Institute of Theoretical Physics and Department of Physics
- Shanxi University
- China
| | - J.-Q. Liang
- Institute of Theoretical Physics and Department of Physics
- Shanxi University
- China
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9
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Xue N, Xie H, Wang Z, Liang JQ. Realization of extreme tunnel magnetoresistance with a molecule-magnet-dimer junction. RSC Adv 2014. [DOI: 10.1039/c4ra12154f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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10
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Cerfontaine P, Botzem T, DiVincenzo DP, Bluhm H. High-fidelity single-qubit gates for two-electron spin qubits in GaAs. PHYSICAL REVIEW LETTERS 2014; 113:150501. [PMID: 25375696 DOI: 10.1103/physrevlett.113.150501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Indexed: 06/04/2023]
Abstract
Single-qubit operations on singlet-triplet qubits in GaAs double quantum dots have not yet reached the fidelities required for fault-tolerant quantum information processing. Considering experimentally important constraints and using measured noise spectra, we numerically minimize the effect of decoherence (including high-frequency 1/f-like noise) and show, theoretically, that quantum gates with fidelities higher than 99.9% are achievable. We also present a self-consistent tuning protocol which should allow the elimination of individual systematic gate errors directly in an experiment.
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Affiliation(s)
- Pascal Cerfontaine
- JARA-Institute for Quantum Information, RWTH Aachen University, D-52074 Aachen, Germany
| | - Tim Botzem
- JARA-Institute for Quantum Information, RWTH Aachen University, D-52074 Aachen, Germany
| | - David P DiVincenzo
- JARA-Institute for Quantum Information, RWTH Aachen University, D-52074 Aachen, Germany and Peter Grünberg Institute: Theoretical Nanoelectronics, Research Center Jülich, D-52425 Jülich, Germany
| | - Hendrik Bluhm
- JARA-Institute for Quantum Information, RWTH Aachen University, D-52074 Aachen, Germany
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11
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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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12
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Abstract
Several logical qubits and quantum gates have been proposed for semiconductor quantum dots controlled by voltages applied to top gates. The different schemes can be difficult to compare meaningfully. Here we develop a theoretical framework to evaluate disparate qubit-gating schemes on an equal footing. We apply the procedure to two types of double-dot qubits: the singlet-triplet and the semiconducting quantum dot hybrid qubit. We investigate three quantum gates that flip the qubit state: a DC pulsed gate, an AC gate based on logical qubit resonance, and a gate-like process known as stimulated Raman adiabatic passage. These gates are all mediated by an exchange interaction that is controlled experimentally using the interdot tunnel coupling g and the detuning [Symbol: see text], which sets the energy difference between the dots. Our procedure has two steps. First, we optimize the gate fidelity (f) for fixed g as a function of the other control parameters; this yields an f(opt)(g) that is universal for different types of gates. Next, we identify physical constraints on the control parameters; this yields an upper bound f(max) that is specific to the qubit-gate combination. We show that similar gate fidelities (~99:5%) should be attainable for singlet-triplet qubits in isotopically purified Si, and for hybrid qubits in natural Si. Considerably lower fidelities are obtained for GaAs devices, due to the fluctuating magnetic fields ΔB produced by nuclear spins.
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13
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Busl M, Granger G, Gaudreau L, Sánchez R, Kam A, Pioro-Ladrière M, Studenikin SA, Zawadzki P, Wasilewski ZR, Sachrajda AS, Platero G. Bipolar spin blockade and coherent state superpositions in a triple quantum dot. NATURE NANOTECHNOLOGY 2013; 8:261-265. [PMID: 23416792 DOI: 10.1038/nnano.2013.7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 01/10/2013] [Indexed: 06/01/2023]
Abstract
Spin qubits based on interacting spins in double quantum dots have been demonstrated successfully. Readout of the qubit state involves a conversion of spin to charge information, which is universally achieved by taking advantage of a spin blockade phenomenon resulting from Pauli's exclusion principle. The archetypal spin blockade transport signature in double quantum dots takes the form of a rectified current. At present, more complex spin qubit circuits including triple quantum dots are being developed. Here we show, both experimentally and theoretically, that in a linear triple quantum dot circuit the spin blockade becomes bipolar with current strongly suppressed in both bias directions and also that a new quantum coherent mechanism becomes relevant. In this mechanism, charge is transferred non-intuitively via coherent states from one end of the linear triple dot circuit to the other, without involving the centre site. Our results have implications for future complex nanospintronic circuits.
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Affiliation(s)
- M Busl
- Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
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14
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Composite pulses for robust universal control of singlet–triplet qubits. Nat Commun 2012; 3:997. [DOI: 10.1038/ncomms2003] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Accepted: 07/11/2012] [Indexed: 11/08/2022] Open
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15
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Brunner R, Shin YS, Obata T, Pioro-Ladrière M, Kubo T, Yoshida K, Taniyama T, Tokura Y, Tarucha S. Two-qubit gate of combined single-spin rotation and interdot spin exchange in a double quantum dot. PHYSICAL REVIEW LETTERS 2011; 107:146801. [PMID: 22107226 DOI: 10.1103/physrevlett.107.146801] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Indexed: 05/31/2023]
Abstract
A crucial requirement for quantum-information processing is the realization of multiple-qubit quantum gates. Here, we demonstrate an electron spin-based all-electrical two-qubit gate consisting of single-spin rotations and interdot spin exchange in a double quantum dot. A partially entangled output state is obtained by the application of the two-qubit gate to an initial, uncorrelated state. We find that the degree of entanglement is controllable by the exchange operation time. The approach represents a key step towards the realization of universal multiple-qubit gates.
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Affiliation(s)
- R Brunner
- Quantum Spin Information Project, ICORP, Japan Science and Technology Agency, Atsugi-shi, Kanagawa, 243-0198, Japan.
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16
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Coello JG, Bayat A, Bose S, Jefferson JH, Creffield CE. Spin filtering and entanglement swapping through coherent evolution of a single quantum dot. PHYSICAL REVIEW LETTERS 2010; 105:080502. [PMID: 20868084 DOI: 10.1103/physrevlett.105.080502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 06/12/2010] [Indexed: 05/29/2023]
Abstract
We exploit the nondissipative dynamics of a pair of electrons in a large square quantum dot to perform singlet-triplet spin measurement through a single charge detection and show how this may be used for entanglement swapping and teleportation. The method is also used to generate the Affleck-Kennedy-Lieb-Tasaki ground state, a further resource for quantum computation. We justify, and derive analytic results for, an effective charge-spin Hamiltonian which is valid over a wide range of parameters and agrees well with exact numerical results of a realistic effective-mass model. Our analysis also indicates that the method is robust to the choice of dot-size and initialization errors, as well as decoherence.
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Affiliation(s)
- Jose Garcia Coello
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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17
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Yokoshi N, Imamura H, Kosaka H. Electrical measurement of a two-electron spin state in a double quantum dot. PHYSICAL REVIEW LETTERS 2009; 103:046806. [PMID: 19659384 DOI: 10.1103/physrevlett.103.046806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Indexed: 05/28/2023]
Abstract
We propose a scheme for electrical measurement of two-electron spin states in a semiconductor double quantum dot. We calculated the adiabatic charge transfer when surface gates are modulated in time. Because of spin-orbit coupling in the semiconductor, spatial displacement of the electrons causes a total spin rotation. It follows that the expectation value of the transferred charge reflects the relative phase as well as the total spin population of a prepared singlet-triplet superposition state. The precise detection of the charge transfer serves to identify the quantum superposition.
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Ribeiro H, Burkard G. Nuclear state preparation via Landau-Zener-Stückelberg transitions in double quantum dots. PHYSICAL REVIEW LETTERS 2009; 102:216802. [PMID: 19519124 DOI: 10.1103/physrevlett.102.216802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Indexed: 05/27/2023]
Abstract
We theoretically model a nuclear-state preparation scheme that increases the coherence time of a two-spin qubit in a double quantum dot. The two-electron system is tuned repeatedly across a singlet-triplet level anticrossing with alternating slow and rapid sweeps of an external bias voltage. Using a Landau-Zener-Stückelberg model, we find that in addition to a small nuclear polarization that weakly affects the electron spin coherence, the slow sweeps are only partially adiabatic and lead to a weak nuclear spin measurement and a nuclear-state narrowing which prolongs the electron spin coherence. This resolves some open problems brought up by a recent experiment [D. J. Reilly, Science 321, 817 (2008).10.1126/science.1159221]. Based on our description of the weak measurement, we simulate a system with up to n=200 nuclear spins per dot. Scaling in n indicates a stronger effect for larger n.
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Affiliation(s)
- Hugo Ribeiro
- Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
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