針對尖峰電路的稀疏且截斷狀態向量模擬器

摘要

在一类称为峰值电路的量子电路中，目标是预测电路输出端最可能出现的比特串。由于此类电路的设计使其输出分布呈现尖锐峰值，理论上应可借助包含有限数量项的截断态向量（即占总概率质量的一部分）对其进行模拟。这种近似模拟可在经典计算机上通过稀疏表示实现——仅存储态向量中的非零振幅，而非多数量子模拟器常见的密集表示。为提升效率，对态向量的所有操作应尽可能实现矢量化，并在可用时利用硬件加速。本文描述了如何在开源实现中达成这些要求，并讨论其性能与局限性。

English

In a class of quantum circuits known as peaked circuits, the goal is to predict the most probable bit string at the output of the circuit. Since these circuits are designed to have a sharp peak in their output distribution, in principle it should be possible to simulate them using a truncated state vector with a limited number of terms, or a fraction of the total probability mass. This approximate simulation can be carried out on a classical computer with a sparse representation that stores only the nonzero amplitudes of the state vector, in contrast to the dense representations that are common in most quantum simulators. For efficiency, all operations on the state vector should be vectorized to the furthest possible extent and, if available, hardware acceleration can also be used. This work describes how these requirements were met in an open-source implementation, and discusses its performance and limitations.