arXiv:2409.01592quant-phcs.LG2024-09被引 2

用经典核方法高效学习量子系统的多体关联,避免昂贵的数值模拟。

Learning out-of-time-ordered correlators with classical kernel methods

  • 将张量网络生成数据,转化为回归任务训练核模型
  • 在40比特系统上实现R²超过0.7167,平均达0.8以上
  • 适合需要快速评估量子混沌行为的研究者

外时间序关联函数(OTOCs)被广泛用于研究量子系统中的信息混淆。然而,经典计算机直接计算OTOCs代价高昂,因需对多体量子系统进行经典模拟,计算成本随系统规模迅速增长。同样,量子计算机精确模拟动态过程,在噪声中等规模量子(NISQ)设备上仅限短时间,而容错量子计算机目前尚不可行。这促使寻找替代方法以确定OTOC及相关量。本研究探索了四个描述一维局部量子系统的参数化哈密顿量集合,考察经典核方法(KMs)能否准确学习XZ-OTOC及特定OTOC之和作为哈密顿量参数的函数。将问题建模为回归任务,利用张量网络方法生成最多40个量子比特的小批量标注数据。训练多种标准核机后发现,拉普拉斯与径向基函数(RBF)核表现最佳,测试集上决定系数(R²)最低达0.7167,各集合平均值在0.8112至0.9822之间,且均方根误差和平均绝对误差均较小。训练完成后,模型可替代后续张量网络计算,用于参数化集合内系统的OTOC函数评估,助力大规模分析。

原文摘要 · Abstract (English)

Out-of-Time Ordered Correlators (OTOCs) are widely used to investigate information scrambling in quantum systems. However, directly computing OTOCs with classical computers is an expensive procedure. This is due to the need to classically simulate the dynamics of quantum many-body systems, which entails computational costs that scale rapidly with system size. Similarly, exact simulation of the dynamics with a quantum computer (QC) will either only be possible for short times with noisy intermediate-scale quantum (NISQ) devices, or will require a fault-tolerant QC which is currently beyond technological capabilities. This motivates a search for alternative approaches to determine OTOCs and related quantities. In this study, we explore four parameterised sets of Hamiltonians describing local one-dimensional quantum systems of interest in condensed matter physics. For each set, we investigate whether classical kernel methods (KMs) can accurately learn the XZ-OTOC and a particular sum of OTOCs, as functions of the Hamiltonian parameters. We frame the problem as a regression task, generating small batches of labelled data with classical tensor network methods for quantum many-body systems with up to 40 qubits. Using this data, we train a variety of standard kernel machines and observe that the Laplacian and radial basis function (RBF) kernels perform best, achieving a coefficient of determination (\(R^2\)) on the testing sets of at least 0.7167, with averages between 0.8112 and 0.9822 for the various sets of Hamiltonians, together with small root mean squared error and mean absolute error. Hence, after training, the models can replace further uses of tensor networks for calculating an OTOC function of a system within the parameterised sets. Accordingly, the proposed method can assist with extensive evaluations of an OTOC function.

量子关联核方法张量网络信息混淆

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