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

• DOI: 10.1021/acs.jctc.2c00807
• Publication Date: 2023-01-27T14:36:15Z
• Authors: Phalgun Lolur; Mårten Skogh; Werner Dobrautz; Christopher Warren; Janka Biznárová; Amr Osman; Giovanna Tancredi; Göran Wendin; Jonas Bylander; Martin Rahm
• Keywords: Other Electrical Engineering, Electronic Engineering, Information Engineering; Other Physics Topics; 0103 physical sciences; Theoretical Chemistry; 01 natural sciences

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 postprocessing 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. Up to 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 demonstrate the scalability of the method.