论文标题
数字量子仿真,学习哈密顿量的学习和踢顶的量子混乱
Digital Quantum Simulation, Learning of the Floquet Hamiltonian, and Quantum Chaos of the Kicked Top
论文作者
论文摘要
踢顶是量子混乱研究中的范式模型之一[F.〜haake等,\ emph {Chaos的量子特征(Springer Series in Synergetics vol 54)}(2018)]。最近,已经显示,踢顶部的量子混乱的开始可能与集体旋转系统的数字量子模拟(DQS)中的猪肉误差的扩散有关。具体而言,猪肉误差的增殖在几体观测值的期望值中显现出来,与关键猪棍步骤的目标动力学强烈偏离,其中随机矩阵理论可以预测踢脚踢的floquet operator的光谱统计。在这项工作中,我们在哈密顿学习框架(HL)中研究了这些现象。我们展示了如何采用最近开发的哈密顿学习方案来重建踢脚式顶部的频道动力学的发电机,即Floquet Hamiltonian。我们进一步展示了HL如何揭示Trotter误差的增殖,因为它向floquet-Magnus膨胀的低阶截断无法近似地描述动力学的过渡。这为在实现动力学的生成器级别上分析猪跑误差开辟了新的实验可能性,可以以可扩展的方式将其推广到量子多体系统的DQ。本文是为了纪念我们的同事和朋友弗里茨·哈克(Fritz Haake)。
The kicked top is one of the paradigmatic models in the study of quantum chaos~[F.~Haake et al., \emph{Quantum Signatures of Chaos (Springer Series in Synergetics vol 54)} (2018)]. Recently it has been shown that the onset of quantum chaos in the kicked top can be related to the proliferation of Trotter errors in digital quantum simulation (DQS) of collective spin systems. Specifically, the proliferation of Trotter errors becomes manifest in expectation values of few-body observables strongly deviating from the target dynamics above a critical Trotter step, where the spectral statistics of the Floquet operator of the kicked top can be predicted by random matrix theory. In this work, we study these phenomena in the framework of Hamiltonian learning (HL). We show how a recently developed Hamiltonian learning protocol can be employed to reconstruct the generator of the stroboscopic dynamics, i.e., the Floquet Hamiltonian, of the kicked top. We further show how the proliferation of Trotter errors is revealed by HL as the transition to a regime in which the dynamics cannot be approximately described by a low-order truncation of the Floquet-Magnus expansion. This opens up new experimental possibilities for the analysis of Trotter errors on the level of the generator of the implemented dynamics, that can be generalized to the DQS of quantum many-body systems in a scalable way. This paper is in memory of our colleague and friend Fritz Haake.