Title

Efficient Step-Merged Quantum Imaginary Time Evolution Algorithm for Quantum Chemistry

Publication Date

9-2-2020

Department

Physics and Astronomy; Ames Laboratory; Electrical and Computer Engineering

Campus Units

Ames Laboratory, Electrical and Computer Engineering, Physics and Astronomy

OSTI ID+

1677505

Report Number

IS-J 10300

DOI

10.1021/acs.jctc.0c00666

Journal Title

Journal of Chemical Theory and Computation

Volume Number

16

Issue Number

10

First Page

6256

Last Page

6266

Abstract

We develop a resource-efficient step-merged quantum imaginary time evolution approach (smQITE) to solve for the ground state of a Hamiltonian on quantum computers. This heuristic method features a fixed shallow quantum circuit depth along the state evolution path. We use this algorithm to determine the binding energy curves of a set of molecules, including H2, H4, H6, LiH, HF, H2O, and BeH2, and find highly accurate results. The required quantum resources of smQITE calculations can be further reduced by adopting the circuit form of the variational quantum eigensolver (VQE) technique, such as the unitary coupled cluster ansatz. We demonstrate that smQITE achieves a similar computational accuracy as VQE at the same fixed-circuit ansatz, without requiring a generally complicated high-dimensional nonconvex optimization. Finally, smQITE calculations are carried out on Rigetti quantum processing units, demonstrating that the approach is readily applicable on current noisy intermediate-scale quantum devices.

DOE Contract Number(s)

AC02-07CH11358

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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