通过多次能量偏移实现量子虚时演化的干涉工程
Interference Engineering for Quantum Imaginary-Time Evolution through Multiple Energy Shifts
AI总结：
本文提出多偏移量子虚时演化（MS-QITE），利用能量偏移的分布设计干涉，通过蒙特卡罗和连续变量辅助两种实现方式优化量子虚时演化，在横向场伊辛模型数值验证中展现出降低资源消耗、提升估计稳定性等优势。
AI中文摘要：
在虚时演化中，能量偏移通常是无关紧要的，因为它仅会改变演化态的归一化。然而在量子计算机上，虚时演化可被实现为实时演化的相干叠加或采样叠加，其中能量偏移会产生可发生干涉的相对相位。本文提出多偏移量子虚时演化（MS-QITE），该方法利用能量偏移的分布来设计干涉并优化不同的实现方案。在蒙特卡罗实现中，多偏移会重塑采样分布并将其集中在更短的实时窗口内，从而缩短所需的哈密顿量演化时间并提高基态能量估计的稳定性。在连续变量辅助实现中，该方法允许对有限正交区间而非单个正交值附近进行后选择，大幅降低资源消耗的同时仍能制备精确的热态。横向场伊辛模型的数值结果表明，能量偏移为优化量子虚时演化提供了一种基于干涉的有效方法。
英文摘要：
Energy shifting is usually trivial in imaginary-time evolution because it changes only the normalization of the evolved state. On a quantum computer, however, imaginary-time evolution can be implemented as a coherent or sampled superposition of real-time evolutions, in which energy shifts generate relative phases that can interfere. Here we introduce multi-shift quantum imaginary-time evolution (MS-QITE), which uses a distribution of energy shifts to engineer this interference and optimize different implementations. In a Monte Carlo realization, multi-shift reshapes the normalized sampling distribution and concentrates it within a shorter real-time window, thereby reducing the typical Hamiltonian-evolution time and improving the stability of ground-state-energy estimation. In a continuous-variable-assisted realization, it enables projection onto a state supported over a finite quadrature interval, substantially reducing the required squeezing over an intermediate temperature range while retaining accurate thermal-state preparation. Numerical results for transverse-field Ising models demonstrate that energy shifts provide an interference-based degree of freedom for optimizing quantum imaginary-time evolution.
