超导量子比特非马尔可夫性的确凿特征
Smoking-gun signatures of non-Markovianity of a superconducting qubit
AI总结：
本文研究了超导transmon量子比特闲置演化的时间相关噪声，利用量子电路理论构建了时间局域主方程，揭示了相干性周期性恢复和额外频率等非马尔可夫特征。
摘要：
我们描述了影响超导transmon量子比特闲置演化的时间相关噪声过程。为了对复合的量子比特-环境系统进行建模，我们使用量子电路理论，并展示了如何为影响量子比特的横向噪声推导电路哈密顿量。基于无时间卷积投影算子方法，我们构建了一个时间局域的主方程，当将其转换为其正则Lindblad形式时，表现出在所有时刻均为负的衰减率，对应于永恒的非马尔可夫动力学。通过在Kraus表示中表达主方程的解，我们识别出两个关键的非马尔可夫现象：相干性的周期性恢复，以及在量子比特态的进动中出现远离量子比特频率的额外频率。当单量子比特门作用于量子比特态时，这些额外频率项会发生不期望的旋转，它们有效地充当了在Bloch球旋转之前该状态的记忆。
英文摘要：
We describe temporally correlated noise processes that influence the idle evolution of a superconducting transmon qubit. To model the composite qubit-environment system we use quantum circuit theory, and we show how a circuit Hamiltonian can be derived for transverse noise affecting the qubit. Based on the time-convolutionless projection operator method, we construct a time-local master equation which, when transformed to its canonical Lindblad form, exhbitis a decay rate that is negative at all times, corresponding to eternally non-Markovian dynamics. By expressing the solution of the master equation in the Kraus representation, we identify two crucial non-Markovian phenomena: periodic revivals of coherence, and the appearance of additional frequencies far from the qubit frequency in the precession of the qubit state. When a single qubit gate acts on the qubit state, these extra frequency terms rotate undesirably and they effectively act as the memory of the state prior to the rotation around the Bloch sphere.
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