Orbital Expansion Variational Quantum Eigensolver: Enabling Efficient Simulation of Molecules with Shallow Quantum Circuit

TL;DR

This paper introduces OE-VQE, a new quantum algorithm that efficiently simulates molecular ground states using shallow circuits by systematically expanding the active space, improving convergence and performance in noisy quantum environments.

Contribution

The paper proposes OE-VQE, a novel framework that constructs an efficient convergence path starting from a compact active space and expanding it, enabling shallower circuit simulations of molecules.

Findings

OE-VQE dramatically improves convergence speed.

Benchmark results show enhanced performance on typical molecules.

Shallower circuits achieve accurate ground state energies.

Abstract

In the noisy-intermediate-scale-quantum era, Variational Quantum Eigensolver (VQE) is a promising method to study ground state properties in quantum chemistry, materials science, and condensed physics. However, general quantum eigensolvers are lack of systematical improvability, and achieve rigorous convergence is generally hard in practice, especially in solving strong-correlated systems. Here, we propose an Orbital Expansion VQE~(OE-VQE) framework to construct an efficient convergence path. The path starts from a highly correlated compact active space and rapidly expands and converges to the ground state, enabling simulating ground states with much shallower quantum circuits. We benchmark the OE-VQE on a series of typical molecules including H$_{6}$-chain, H$_{10}$-ring and N$_2$, and the simulation results show that proposed convergence paths dramatically enhance the performance of general quantum eigensolvers.