论文标题

抵绝粉优化的本地驾驶

Counterdiabatic Optimised Local Driving

论文作者

Čepaitė, Ieva, Polkovnikov, Anatoli, Daley, Andrew J., Duncan, Callum W.

论文摘要

绝热协议是在各种量子技术中采用的,从实施状态制备和较大设备的基本操作到量子退火和绝热量子计算中的高级协议。加速这些过程的问题引起了很大的兴趣,导致了一种方法,最著名的是量子的最佳控制和对绝热性的快捷方式。这两种方法是互补的:最佳控制操纵控制场以在最小允许的时间中引导动力学,同时捷径到绝热性的旨在在加速时保留绝热状况。我们概述了一种结合两种方法并利用每种方法的优势的新方法。随着时间依赖性控制场的添加,新技术在近似局部的抵绝热驾驶中改善。我们将这种新方法称为反绝热优化的本地驾驶(COLD),我们表明,当应用于退火方案,状态制备方案,纠缠产生和人口转移时,它可能会大大改善。我们还展示了一种新方法来优化控制场,该方法不需要访问波函数或系统动力学的计算。可以通过现有的高级最佳控制方法来增强冷的状态,我们使用切碎的随机基础方法和梯度上升脉冲工程来探讨这一点。

Adiabatic protocols are employed across a variety of quantum technologies, from implementing state preparation and individual operations that are building blocks of larger devices, to higher-level protocols in quantum annealing and adiabatic quantum computation. The problem of speeding up these processes has garnered a large amount of interest, resulting in a menagerie of approaches, most notably quantum optimal control and shortcuts to adiabaticity. The two approaches are complementary: optimal control manipulates control fields to steer the dynamics in the minimum allowed time while shortcuts to adiabaticity aim to retain the adiabatic condition upon speed-up. We outline a new method which combines the two methodologies and takes advantage of the strengths of each. The new technique improves upon approximate local counterdiabatic driving with the addition of time-dependent control fields. We refer to this new method as counterdiabatic optimised local driving (COLD) and we show that it can result in a substantial improvement when applied to annealing protocols, state preparation schemes, entanglement generation and population transfer on a lattice. We also demonstrate a new approach to the optimisation of control fields which does not require access to the wavefunction or the computation of system dynamics. COLD can be enhanced with existing advanced optimal control methods and we explore this using the chopped randomised basis method and gradient ascent pulse engineering.

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