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)
