改进离散时间演化的简单方法
Simple Ways to improve Discrete Time Evolution
AI总结:
本文提出将针对两算子优化的Suzuki-Trotter方案推广至多算子分解,并指出泰勒或切比雪夫展开优于某些情况下的Suzuki-Trotter,还给出了基于复零点线性因式分解的稳定截断多项式方法。
摘要:
Suzuki-Trotter分解,如$\exp(Ht)$这样的指数算子分解,在数值物理的几乎所有分支中都是必需的。通常,所考虑的指数需要被拆分成两个以上的算子,例如在量子计算机上作为局部门。在这项工作中,我们展示了如何将原本为恰好两个算子设计的高度优化方案应用于这种通用的Suzuki-Trotter分解。在第一个技巧之后,我们解释了是什么构成了一个高效的分解,以及如何从大量可用的方案中进行选择。此外,我们证明了许多问题,对于这些问题,Suzuki-Trotter分解可能看起来是规范性的ansatz,但用不同的方法(如Taylor或Chebyshev展开)来处理会更好。特别是,我们推导了一种高效且数值稳定的方法,基于其复零点进行线性因式分解来实现截断多项式展开。
英文摘要:
Suzuki-Trotter decompositions of exponential operators like $\exp(Ht)$ are required in almost every branch of numerical physics. Often the exponent under consideration has to be split into more than two operators, for instance as local gates on quantum computers. In this work, we demonstrate how highly optimised schemes originally derived for exactly two operators can be applied to such generic Suzuki-Trotter decompositions. After this first trick, we explain what makes an efficient decomposition and how to choose from the large variety available. Furthermore we demonstrate that many problems for which a Suzuki-Trotter decomposition might appear to be the canonical ansatz, are better approached with different methods like Taylor or Chebyshev expansions. In particular, we derive an efficient and numerically stable method to implement truncated polynomial expansions based on a linear factorisation using their complex zeros.
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