Subspace variational quantum simulator

Quantum simulation is one of the key applications of quantum computing, which accelerates research and development in the fields such as chemistry and material science. The recent development of noisy intermediate-scale quantum (NISQ) devices urges the exploration of applications without the necessi...

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Bibliographic Details
Main Authors: Kentaro Heya, Ken M. Nakanishi, Kosuke Mitarai, Zhiguang Yan, Kun Zuo, Yasunari Suzuki, Takanori Sugiyama, Shuhei Tamate, Yutaka Tabuchi, Keisuke Fujii, Yasunobu Nakamura
Format: Article
Language:English
Published: American Physical Society 2023-05-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.023078
Description
Summary:Quantum simulation is one of the key applications of quantum computing, which accelerates research and development in the fields such as chemistry and material science. The recent development of noisy intermediate-scale quantum (NISQ) devices urges the exploration of applications without the necessity of quantum error correction. In this paper, we propose an efficient method to simulate quantum dynamics driven by a static Hamiltonian on NISQ devices, named subspace variational quantum simulator (SVQS). SVQS employs the subspace-search variational quantum eigensolver (SSVQE) [Phys. Rev. Res. 1, 033062 (2019)2643-156410.1103/PhysRevResearch.1.033062] to find a low-lying eigensubspace and extends it to simulate dynamics within the subspace with lower overhead compared to the existing schemes. We experimentally simulate the time-evolution operator in a low-lying eigensubspace of a hydrogen molecule. We also define the subspace process fidelity as a measure between two quantum processes in a subspace. The subspace time evolution mimicked by SVQS shows the subspace process fidelity of 0.896–0.989.
ISSN:2643-1564