Reference-State Error Mitigation: A Strategy for High Accuracy Quantum Computation of Chemistry

TL;DR

This paper presents a simple, hardware-efficient error mitigation strategy called reference-state error mitigation (REM) for quantum chemistry calculations on near-term quantum computers, significantly improving accuracy.

Contribution

The paper introduces REM, a novel error mitigation method compatible with current quantum hardware that enhances the accuracy of quantum chemistry simulations without extensive additional measurements.

Findings

Achieved two orders-of-magnitude improvement in ground state energy accuracy for small molecules.

Demonstrated effectiveness of REM on superconducting quantum hardware.

Showed scalability of the method through simulations of deep noisy circuits.

Abstract

Decoherence and gate errors severely limit the capabilities of state-of-the-art quantum computers. This work introduces a strategy for reference-state error mitigation (REM) of quantum chemistry that can be straightforwardly implemented on current and near-term devices. REM can be applied alongside existing mitigation procedures, while requiring minimal post-processing and only one or no additional measurements. The approach is agnostic to the underlying quantum mechanical ansatz and is designed for the variational quantum eigensolver (VQE). Two orders-of-magnitude improvement in the computational accuracy of ground state energies of small molecules (H2, HeH+ and LiH) is demonstrated on superconducting quantum hardware. Simulations of noisy circuits with a depth exceeding 1000 two-qubit gates are used to argue for scalability of the method.