Preparing random states and benchmarking with many-body quantum chaos
Preparing random states and benchmarking with many-body quantum chaos
复制标题
DOI：
10.1038/s41586-022-05442-1
复制
发表时间：
2023-01-19
期刊：
影响因子：
64.8
通讯作者：
Endres, Manuel
中科院分区：
文献类型：
--
作者：
Choi, Joonhee;Shaw, Adam L. L.;Endres, Manuel
随机产生量子态在现代量子科学中变得越来越重要，其应用既有理论意义也有实际意义。特别是，这种随机分布但纯粹的量子态的集合奠定了我们对量子电路(1)和黑洞(2)的复杂性的理解，并已在量子优势（5,6）的测试中用于对量子器件（3,4）进行基准测试。然而，创建随机集成需要高度的时空控制（7-12），这使得此类研究无法用于广泛的量子系统。在这里，我们通过预测和实验观察在时间无关的哈密顿动力学下自然出现的随机状态集成来解决这个问题，我们使用它来实现一个有效的，广泛适用的基准协议。观测到的随机系综来自于射影测量，并且与大量子系统子系统之间建立的普遍相关性密切相关，为量子热化提供了新的见解（13）。基于这一发现，我们开发了一种保真度估计方案，我们使用少于10(4)个实验样本对具有多达25个原子的里德伯量子模拟器进行了演示。这种方法具有广泛的适用性，正如我们在哈密顿参数估计、目标状态生成基准测试以及模拟和数字量子器件的比较中所展示的那样。我们的工作对理解量子动力学中的随机性具有启示意义（14），并使这一概念能够在更广泛的背景下应用（4,5,9,10,15-20）。
Producing quantum states at random has become increasingly important in modern quantum science, with applications being both theoretical and practical. In particular, ensembles of such randomly distributed, but pure, quantum states underlie our understanding of complexity in quantum circuits(1) and black holes(2), and have been used for benchmarking quantum devices(3,4) in tests of quantum advantage(5,6). However, creating random ensembles has necessitated a high degree of spatio-temporal control(7-12) placing such studies out of reach for a wide class of quantum systems. Here we solve this problem by predicting and experimentally observing the emergence of random state ensembles naturally under time-independent Hamiltonian dynamics, which we use to implement an efficient, widely applicable benchmarking protocol. The observed random ensembles emerge from projective measurements and are intimately linked to universal correlations built up between subsystems of a larger quantum system, offering new insights into quantum thermalization(13). Predicated on this discovery, we develop a fidelity estimation scheme, which we demonstrate for a Rydberg quantum simulator with up to 25 atoms using fewer than 10(4) experimental samples. This method has broad applicability, as we demonstrate for Hamiltonian parameter estimation, target-state generation benchmarking, and comparison of analogue and digital quantum devices. Our work has implications for understanding randomness in quantum dynamics(14) and enables applications of this concept in a much wider context(4,5,9,10,15-20).