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Robust quantum control with disorder-dressed evolution
2023-03-23 10:58

近日,瑞士苏黎世联邦理工学院的Tenzan Araki与日本理化研究所理论量子物理实验室的Clemens Gneiting等人合作,成功实现了具有无序演化的鲁棒量子控制。相关研究成果已于2023年3月17日在国际权威学术期刊《物理评论A》上发表。

该研究团队使用无序修饰演化方程来识别鲁棒控制脉冲。该方程通过描述无序的量子主方程,捕获了无序效应,这里的无序指的是脉冲扰动,以描述无序平均密度矩阵的演化。在这种鲁棒控制方法中,最终状态的纯度表明了基础控制脉冲的鲁棒性,如果最终状态是纯的(并且与目标状态相符),则可以选择这个鲁棒控制脉冲。研究人员证明了该原则可以成功地用于寻找鲁棒控制脉冲。为此,他们采用了适用于无序修饰演化的Krotov方法,并展示了其在几个单量子比特控制任务中的应用。

据了解,最优量子控制理论旨在确定能够高效产生所需目标态的时变控制哈密顿量。因此,在成功设计和开发量子技术方面,该理论发挥着至关重要的作用。但是,通常情况下,提供的控制脉冲对微小扰动非常敏感,这可能会使在实验中可靠地使用这些脉冲变得困难甚至不可能。鲁棒量子控制旨在通过找到即使在脉冲扰动存在的情况下也能够再现目标态的控制脉冲来缓解这个问题。然而,找到这样的鲁棒控制脉冲通常很困难,因为评估控制脉冲需要考虑所有可能的失真版本。

附:英文原文

Title: Robust quantum control with disorder-dressed evolution

Author: Tenzan Araki, Franco Nori, Clemens Gneiting

Issue&Volume: 2023/03/17

Abstract: The theory of optimal quantum control serves to identify time-dependent control Hamiltonians that efficiently produce desired target states. As such, it plays an essential role in the successful design and development of quantum technologies. However, often the delivered control pulses are exceedingly sensitive to small perturbations, which can make it hard if not impossible to reliably deploy these in experiments. Robust quantum control aims at mitigating this issue by finding control pulses that uphold their capacity to reproduce the target states even in the presence of pulse perturbations. However, finding such robust control pulses is generically hard, since the assessment of control pulses requires the inclusion of all possible distorted versions in the evaluation. Here we show that robust control pulses can be identified based on disorder-dressed evolution equations. The latter capture the effect of disorder, which here stands for the pulse perturbations, in terms of quantum master equations describing the evolution of the disorder-averaged density matrix. In this approach to robust control, the purities of the final states indicate the robustness of the underlying control pulses, and robust control pulses are singled out if the final states are pure (and coincide with the target states). We show that this principle can be successfully employed to find robust control pulses. To this end, we adapt Krotov's method for disorder-dressed evolution and demonstrate its application with several single-qubit control tasks.

DOI: 10.1103/PhysRevA.107.032609

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.107.032609

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