Chee, C. H., Mak, A. M., Leykam, D., Kl Barkoutsos, P., & Angelakis, D. G. (2024). Computing electronic correlation energies using linear depth quantum circuits. Quantum Science and Technology, 9(2), 025003. https://doi.org/10.1088/2058-9565/ad1f3a
Abstract:
Abstract
Efficient computation of molecular energies is an exciting application of quantum computing for quantum chemistry, but current noisy intermediate-scale quantum (NISQ) devices can only execute shallow circuits, limiting existing variational quantum algorithms, which require deep entangling quantum circuit ansatzes to capture correlations, to small molecules. Here we demonstrate a variational NISQ-friendly algorithm that generates a set of Hartree–Fock ansatzes using multiple shallow circuits with depth linear in the number of qubits to estimate electronic correlation energies via perturbation theory up to the second order. We tested the algorithm on several small molecules, both with classical simulations including noise models and on cloud quantum processors, showing that it not only reproduces the equilibrium molecular energies but it also captures the perturbative electronic correlation effects at longer bond distances. The number of shallow circuits required for our algorithms scales
O
(
N
5
)
, with N being the system size, thus enabling the study of larger molecules compared to other approaches, where circuit depth or number of qubits required become prohibitive for NISQ devices.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the National Research Foundation / A*STAR - Quantum Engineering Programme
Grant Reference no. : NRF-2021-QEP-02-P02
A*STAR (#21709)
Description:
This is the Accepted Manuscript version of an article accepted for publication in Quantum Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/2058-9565/ad1f3a