A circuit-generated quantum subspace algorithm for the variational quantum eigensolver

作     者：Hirsbrunner, Mark R. Mullinax, J. Wayne Shen, Yizhi Williams-Young, David B. Klymko, Katherine Van Beeumen, Roel Tubman, Norm M. 

作者机构：Department of Physics University of Illinois at Urbana-Champaign UrbanaIL61801 United States USRA Research Institute for Advanced Computer Science Mountain ViewCA94043 United States KBR Inc. NASA Ames Research Center Moffett FieldCA94035 United States Intelligent Systems Division NASA Ames Research Center Moffett FieldCA94035 United States Applied Mathematics and Computational Research Division Lawrence Berkeley National Lab BerkeleyCA94720 United States NERSC Lawrence Berkeley National Lab BerkeleyCA94720 United States 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2024年

核心收录：

主　　题：Ground state 

摘      要：Recent research has shown that wavefunction evolution in real- and imaginary-time can generate quantum subspaces with significant utility for obtaining accurate ground state energies. Inspired by these methods, we propose combining quantum subspace techniques with the variational quantum eigensolver (VQE). In our approach, the parameterized quantum circuit is divided into a series of smaller subcircuits. The sequential application of these subcircuits to an initial state generates a set of wavefunctions that we use as a quantum subspace to obtain high-accuracy groundstate energies. We call this technique the circuit subspace variational quantum eigensolver (CSVQE) algorithm. By benchmarking CSVQE on a range of quantum chemistry problems, we show that it can achieve significant error reduction in the best case compared to conventional VQE, particularly for poorly optimized circuits, greatly improving convergence rates. Furthermore, we demonstrate that when applied to circuits trapped at a local minima, CSVQE can produce energies close to the global minimum of the energy landscape, making it a potentially powerful tool for diagnosing local minima. © 2024, CC BY-NC-SA.