论文标题
量子算法，用于评估操作员大小的尺寸
Quantum algorithm for evaluating operator size with Bell measurements
论文作者
论文摘要
操作员的尺寸增长描述了量子动力学中操作员的争夺，并作为表征量子混乱的基本物理概念而脱颖而出。重要的是，仍然没有一个直接测量量子计算机上操作员尺寸的方案。在这里，我们提出了一种量子算法，用于直接测量基于铃铛测量的操作员尺寸及其分布。用自旋链验证了该算法，同时，分析了Trotterization误差和量子噪声的影响。据显示，操作员尺寸生长的饱和可能是由于量子混乱本身引起的，也可能是量子噪声的结果，量子噪声使噪声量子处理器上的量子集成和混沌系统难以区分。然而，发现缓解误差将有效地减少噪声的影响，从而恢复量子混沌系统的区分性。我们的工作提供了可行的协议，用于通过测量操作员的尺寸增长来调查噪声量子计算机上的量子混乱。
Operator size growth describes the scrambling of operators in quantum dynamics and stands out as an essential physical concept for characterizing quantum chaos. Important as it is, a scheme for direct measuring operator size on a quantum computer is still absent. Here, we propose a quantum algorithm for direct measuring the operator size and its distribution based on Bell measurement. The algorithm is verified with spin chains and meanwhile, the effects of Trotterization error and quantum noise are analyzed. It is revealed that saturation of operator size growth can be due to quantum chaos itself or be a consequence of quantum noises, which make a distinction between quantum integrable and chaotic systems difficulty on noisy quantum processors. Nevertheless, it is found that the error mitigation will effectively reduce the influence of noise, so as to restore the distinguishability of quantum chaotic systems. Our work provides a feasible protocol for investigating quantum chaos on noisy quantum computers by measuring operator size growth.
