Precise qubit control beyond the rotating wave approximation

Scheuer, Jochen; Kong, Xinggong; Said, Ressa S.; Chen, J.; Kurz, Andrea; Marseglia, Luca; Du, Jiangfeng; Hemmer, Philip; Montangero, Simone; Calarco, Tommaso; Naydenov, Boris; Jelezko, Fedor

doi:10.1088/1367-2630/16/9/093022

Cited by 78 publications

(96 citation statements)

References 34 publications

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“…Pulse optimization is common in NMR [17] and is also receiving increasing attention in quantum information [12,[18][19][20][21][22][23][24]. In contrast to these previous approaches, our optimization is specifically tailored to the ST-qubit system and includes not only the relevant physical effects but also the most important hardware constraints and the effect of high-frequency nonMarkovian noise.…”

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confidence: 99%

High-Fidelity Single-Qubit Gates for Two-Electron Spin Qubits in GaAs

et al. 2014

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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 non-Markovian 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.One well-established possibility to realize a qubit with electron spins in a semiconductor is to use the m s = 0 spin singlet and triplet states of two electrons as computational basis states [1]. In contrast to single electron spins this encoding allows for all-electrical qubit control. Very long coherence times of up to 200 µs [2], all aspects of single-qubit operation (e.g. initialization [3] and single-shot readout [4]) and a first two-qubit gate [5] have been demonstrated experimentally for such singlettriplet (ST) qubits in GaAs quantum dots. Universal single-qubit control was also shown [6] but subject to large uncharacterized errors. Limiting control error rates to ∼ 10 −3 is a crucial requirement for fault tolerant quantum computing with quantum error correction (QEC) [7][8][9]. Estimates based on coherence time measurements [2,10] indicate that very high gate fidelities should be possible for GaAs-based two-electron spin qubits. However, nonlinearities in the electric control and experimental constraints make the direct application of control methods such as Rabi driving difficult.Previous theoretical work has shown how universal control on the single-and two-qubit level can be achieved in the face of limited dynamic control range [11]. Additionally, gating sequences which are insensitive to slow (quasistatic) control fluctuations have been proposed for this qubit system [12][13][14][15]. While these proposals provide very useful conceptual guidance, a direct implementation will be impeded by experimental constraints such as finite pulse rise times and sampling rate of voltage pulses. Likewise, decoherence effects caused by charge noise [10] and nuclear spin fluctuations [16] have a significant effect.In this letter we use numerical pulse optimization to address the problems posed by systematic inaccuracies and decoherence. Pulse optimization is common in NMR [17] and is also receiving increasing attention in quantum information [12,[18][19][20][21][22][23][24]. In contrast to these previous approaches, our optimization is specifically tailored to the ST-qubit system and includes not only the relevant physical effects but also the most important hardware constraints and the effect of high-frequency nonMarkovian noise. We use experimentally determined parameters and noise spectra [10,16,25] to compute expected gate fidelities and find implementations with no systematic errors and optimized robustness to both slow and fas...

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confidence: 99%

High-Fidelity Single-Qubit Gates for Two-Electron Spin Qubits in GaAs

et al. 2014

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“…At the boundary times, t b = 0, t f , the conditions given by Eq. (28) imply that lim t→t b (θ cot θ cot α) = −2α(t b ), see Eq. (27).…”

Section: Invariant-based Inverse Engineeringmentioning

confidence: 99%

“…This is a simple alternative to a more sophisticated optimal-control-theory approach [28] or bang-bang methods [29]. In a numerical example we first set the reference parameters, t f = 0.1 µs, ω 0 = 2π × 5 GHz, A = (2π) 2 × 506.606 MHz 2 , a = (2π) 2 × 254.648 MHz 2 , and Ω 0 = 2π × 2 GHz, for which the Hamiltonian within and without the RWA give similar dynamics with unsuccessful population inversions, see Fig.…”

Section: B Pulse With Many Field Oscillationsmentioning

confidence: 99%

Pulse design without the rotating-wave approximation

Ibáñez

Chen

et al. 2015

Phys. Rev. A

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We design realizable time-dependent semiclassical pulses to invert the population of a two-level system faster than adiabatically when the rotating-wave approximation cannot be applied. Different approaches, based on the counterdiabatic method or on invariants, may lead to singularities in the pulse functions. Ways to avoid or cancel the singularities are put forward when the pulse spans few oscillations. For many oscillations an alternative numerical minimization method is proposed and demonstrated.

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“…Optimal control methods have been applied to several quantum information processing tasks with NV centres, [17][18][19][20][21][22] affirming their necessity and significance for quantum technology. However, the previously reported experiments, [17][18][19][20][21][22] utilise openloop optimisation techniques where the optimisation is performed before the actual experiment by separate computer simulations.…”

Section: Introductionmentioning

confidence: 99%

“…However, the previously reported experiments, [17][18][19][20][21][22] utilise openloop optimisation techniques where the optimisation is performed before the actual experiment by separate computer simulations. The technique requires system-environment coupling information as detailed as possible to provide a robust solution.…”

Section: Introductionmentioning

confidence: 99%

Autonomous calibration of single spin qubit operations

et al. 2017

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Fully autonomous precise control of qubits is crucial for quantum information processing, quantum communication, and quantum sensing applications. It requires minimal human intervention on the ability to model, to predict, and to anticipate the quantum dynamics, as well as to precisely control and calibrate single qubit operations. Here, we demonstrate single qubit autonomous calibrations via closed-loop optimisations of electron spin quantum operations in diamond. The operations are examined by quantum state and process tomographic measurements at room temperature, and their performances against systematic errors are iteratively rectified by an optimal pulse engineering algorithm. We achieve an autonomous calibrated fidelity up to 1.00 on a time scale of minutes for a spin population inversion and up to 0.98 on a time scale of hours for a single qubit π 2 -rotation within the experimental error of 2%. These results manifest a full potential for versatile quantum technologies.npj Quantum Information (2017) 3:48 ; doi:10.1038/s41534-017-0049-8 INTRODUCTIONThe ability to precisely control and calibrate single qubit operations in solids is a key element for reliable and scalable high-performance quantum technologies, for instance quantumenhanced sensors and metrological devices. It is also the backbone of many quantum information processing tasks, which paves the way for the future realisation of quantum computation and communication. Together with efficient quantum system characterisations and dynamical predictions, 1,2 where human intervention is minimised, autonomous calibration of a single spin qubit is necessary for the realisation of such advanced quantum technologies. We report here experimental demonstrations of the autonomous calibration of a single spin qubit in diamond using closed-loop optimisation. Our spin qubit implementation is a single nitrogen-vacancy (NV) colour centre in diamond. It provides a suitable platform for a precise qubit manipulation to be realised. 3,4 Its remarkable features, such as optical initialisation and readout, and the ability to be manipulated by microwave fields at room temperature, make this physical system extremely attractive for many quantum technologies. 5 We have witnessed a vast array of demonstrations of the NV centres showing a great potential for future technologies, ranging from sub pico-Tesla magnetometry, 6 electric field and temperature sensing, 7,8 to probing molecular dynamics, 9 and single-cell magnetic imaging. 10 Furthermore, intertwinements between quantum information and metrology using NV centre-based systems yield novel and effective techniques towards the realisation of high-performance technologies, e.g. applying quantum error correction 11 and phase estimation 12 to improve magnetic field sensitivity. One way to reach such technology is to apply the closed-loop optimisation method for auto-calibrating the controls required to drive the system in the presence of experimental limitations and noise. Closed-loop optimal control has been already applied...

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Precise qubit control beyond the rotating wave approximation

Abstract: applications in magnetic resonance, quantum computing, quantum optics, and broadband magnetometry., we apply a magnetic field 2 New J. Phys. 16 (2014) 093022 J Scheuer et al 7 New J. Phys. 16 (2014) 093022 J Scheuer et al

Cited by 78 publications

References 34 publications

High-Fidelity Single-Qubit Gates for Two-Electron Spin Qubits in GaAs

High-Fidelity Single-Qubit Gates for Two-Electron Spin Qubits in GaAs

Pulse design without the rotating-wave approximation

Autonomous calibration of single spin qubit operations

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