Optimal control of fast and high-fidelity quantum gates with electron and nuclear spins of a nitrogen-vacancy center in diamond

Chou, Yu‐Min; Goan, Hsi‐Sheng

doi:10.1103/physreva.91.052315

Cited by 37 publications

(19 citation statements)

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“…This theory allows designing more complex pulses in order to find the temporal shape of the external perturbation that makes the evolution operator equal to a predefined gate, as shown for the first time by Palao and Kosloff [39]. Numerous later calculations employing similar schemes have been reported [40][41][42][43][44][45][46]. We illustrate its application to the efficient control of molecular spin qudits by performing numerical simulations on a d = 8 qudit encoded in the S = 7/2 spin states of a simple molecular cluster hosting a Gd 3+ ion (Fig.…”

Section: Introductionmentioning

confidence: 96%

Optimal control of molecular spin qudits

Castro¹,

Carrizo²,

Zueco³

et al. 2021

Preprint

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We demonstrate, numerically, the possibility of manipulating the spin states of molecular nanomagnets with shaped microwave pulses designed with quantum optimal control theory techniques. The state-to-state or full gate transformations can be performed in this way in shorter times than using simple monochromatic resonant pulses. This enhancement in the operation rates can therefore mitigate the effect of decoherence. The optimization protocols and their potential for practical implementations are illustrated by simulations performed for a simple molecular cluster hosting a single Gd 3+ ion. Its eight accessible levels (corresponding to a total spin S = 7/2) allow encoding an 8-level qudit or a system of three coupled qubits. All necessary gates required for universal operation can be obtained with optimal pulses using the intrinsic couplings present in this system. The application of optimal control techniques can facilitate the implementation of quantum technologies based on molecular spin qudits.

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Section: Introductionmentioning

confidence: 96%

Optimal control of molecular spin qudits

Castro¹,

Carrizo²,

Zueco³

et al. 2021

Preprint

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“…Controlling quantum spin dynamics using time-dependent Hamiltonians in the form of pulses (e.g. radiofrequency, microwave, and laser pulses) is the essence of method development in many areas of science [1], from magnetic resonance spectroscopy and imaging [2] and terahertz technologies [3,4] to trapped ions [5], cold atoms [6] and NV-centers in diamond [7,8] for quantum information processing and computing [9].…”

Section: Introductionmentioning

confidence: 99%

Optimal Control of Spins by Analytical Lie Algebraic Derivatives

Foroozandeh¹,

Singh²

2020

Preprint

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Computation of derivatives (gradient and Hessian) of a fidelity function is one of the most crucial steps in many optimization algorithms. Having access to accurate methods to calculate these derivatives is even more desired where the optimization process requires propagation of these calculations over many steps, which is in particular important in optimal control of spin systems. Here we propose a novel numerical approach, ESCALADE (Efficient Spin Control using Analytical Lie Algebraic Derivatives) that offers the exact first and second derivatives of the fidelity function by taking advantage of the properties of the Lie group of 2 × 2 Hermitian matrices, SU(2), and its Lie algebra, the Lie algebra of skew-Hermitian matrices, su(2). A full mathematical treatment of the proposed method along with some numerical examples are presented.

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“…Open algorithms include open versions of GRAPE [23] and Krotov methods [24]. Density matrix centered algorithms were successfully used in some applications of small system size [28][29][30][31]. While traditional propagation * abdelhafez@uchicago.edu requires consistent matrix multiplications and exponentials of superoperators of dimension d 2 × d 2 , some more recent approaches rely on propagating the density matrix through different integration methods [32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Gradient-based optimal control of open quantum systems using quantum trajectories and automatic differentiation

2019

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We present a gradient-based optimal-control technique for open quantum systems that utilizes quantum trajectories to simulate the quantum dynamics during optimization. Using trajectories allows for optimizing open systems with less computational cost than the regular density matrix approaches in most realistic optimization problems. We introduce an improved-sampling algorithm which minimizes the number of trajectories needed per optimization iteration. Together with employing stochastic gradient descent techniques, this reduces the complexity of optimizing many realistic open quantum systems to the complexity encountered with closed systems. Our optimizer harnesses automatic differentiation to provide flexibility in optimization and to suit the different constraints and diverse parameter regimes of real-life experiments. We utilize the optimizer in a variety of applications to demonstrate how the use of quantum trajectories significantly reduces the computation complexity while achieving a multitude of simultaneous optimization targets. Demonstrated targets include high state-transfer fidelities despite dissipation, faster gate times and maximization of qubit-readout fidelity while maintaining the quantum non-demolition nature of the measurement and allowing for subsequent fast resonator reset. arXiv:1901.05541v1 [quant-ph]

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Optimal control of fast and high-fidelity quantum gates with electron and nuclear spins of a nitrogen-vacancy center in diamond

Cited by 37 publications

References 100 publications

Optimal control of molecular spin qudits

Optimal control of molecular spin qudits

Optimal Control of Spins by Analytical Lie Algebraic Derivatives

Gradient-based optimal control of open quantum systems using quantum trajectories and automatic differentiation

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