Smart Scott E, Welakuh Davis M, Narang Prineha
College of Letters and Science, Physical Sciences Division, University of California, Los Angeles, California 90095, United States.
J Chem Theory Comput. 2024 May 14;20(9):3580-3589. doi: 10.1021/acs.jctc.4c00030. Epub 2024 May 1.
Calculating ground and excited states is an exciting prospect for near-term quantum computing applications, and accurate and efficient algorithms are needed to assess viable directions. We develop an excited-state approach based on the contracted quantum eigensolver (ES-CQE), which iteratively attempts to find a solution to a contraction of the Schrödinger equation projected onto a subspace and does not require a priori information on the system. We focus on the anti-Hermitian portion of the equation, leading to a two-body unitary ansatz. We investigate the role of symmetries, initial states, constraints, and overall performance within the context of the model strongly correlated rectangular H system. We show that the ES-CQE achieves near-exact accuracy across the majority of states, covering regions of strong and weak electron correlation, while also elucidating challenging instances for two-body unitary ansatz.
计算基态和激发态对于近期量子计算应用来说是一个令人兴奋的前景，并且需要准确且高效的算法来评估可行的方向。我们基于收缩量子本征求解器（ES-CQE）开发了一种激发态方法，该方法迭代地尝试找到投影到子空间上的薛定谔方程收缩的解，并且不需要关于系统的先验信息。我们关注方程的反厄米部分，从而得到一个两体酉假设。我们在强关联矩形H模型的背景下研究对称性、初始态、约束和整体性能的作用。我们表明，ES-CQE在大多数状态下都能达到近乎精确的精度，涵盖强电子关联和弱电子关联区域，同时也阐明了两体酉假设面临挑战的情况。
