Variational quantum eigensolver boosted by adiabatic connection

TL;DR

This paper combines the variational quantum eigensolver with adiabatic connection methods to efficiently simulate complex chemical systems on near-term quantum computers, improving accuracy without extra quantum resources.

Contribution

It introduces a VQE-AC hybrid approach that enhances quantum simulation accuracy for strongly correlated molecules without increasing quantum resource demands.

Findings

Significant improvement in simulating N₂ dissociation.

Effective modeling of tetramethyleneethane biradical.

No additional quantum measurement requirements for AC corrections.

Abstract

In this work we integrate the variational quantum eigensolver (VQE) with the adiabatic connection (AC) method for efficient simulations of chemical problems on near-term quantum computers. Orbital optimized VQE methods are employed to capture the strong correlation within an active space and classical AC corrections recover the dynamical correlation effects comprising electrons outside of the active space. On two challenging strongly correlated problems, namely the dissociation of N$_2$ and the electronic structure of the tetramethyleneethane biradical, we show that the combined VQE-AC approach enhances the performance of VQE dramatically. Moreover, since the AC corrections do not bring any additional requirements on quantum resources or measurements, they can literally boost the VQE algorithms. Our work paves the way towards quantum simulations of real-life problems on near-term quantum computers.