Extending qubit coherence by adaptive quantum environment learning
Extending qubit coherence by adaptive quantum environment learning
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DOI：
10.1088/1367-2630/ab7bf3
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发表时间：
2019-11
影响因子：
3.3
通讯作者：
Eleanor Scerri;E. Gauger;C. Bonato
中科院分区：
文献类型：
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作者：
Eleanor Scerri;E. Gauger;C. Bonato
退相干是由量子比特与其环境之间的非期望相互作用引起的，对量子技术的发展提出了严峻的挑战。最近，研究人员已经开始分析如何使用实时哈密顿学习方法来抵消退相干，该方法基于对量子比特状态的估计快于环境波动。在这项工作中，我们研究了如何利用学习过程中使用的量子测量的反向作用来扩展量子比特相干性。我们提出了一种自适应协议，通过学习量子比特环境，缩小可能环境状态的分布。虽然量子测量的结果是随机的，但我们表明测量设置的实时适应（基于先前的结果）允许浴分布宽度的确定性减少，从而增加量子位相干性。我们数值模拟了金刚石中氮空位中心在13C核自旋的稀释浴中的电子自旋的性能，发现比非自适应策略的性能有相当大的改进。
Decoherence, resulting from unwanted interaction between a qubit and its environment, poses a serious challenge towards the development of quantum technologies. Recently, researchers have started analysing how real-time Hamiltonian learning approaches, based on estimating the qubit state faster than the environmental fluctuations, can be used to counteract decoherence. In this work, we investigate how the back-action of the quantum measurements used in the learning process can be harnessed to extend qubit coherence. We propose an adaptive protocol that, by learning the qubit environment, narrows down the distribution of possible environment states. While the outcomes of quantum measurements are random, we show that real-time adaptation of measurement settings (based on previous outcomes) allows a deterministic decrease of the width of the bath distribution, and hence an increase of the qubit coherence. We numerically simulate the performance of the protocol for the electronic spin of a nitrogen-vacancy centre in diamond subject to a dilute bath of 13C nuclear spin, finding a considerable improvement over the performance of non-adaptive strategies.