Numerical Simulations of Noisy Quantum Circuits for Computational Chemistry

Opportunities afforded by near-term quantum computers to simulate the properties of small molecules depend on the structure of the computational ansatz as well as the errors induced by device noise. Here we examine the influence of these factors on the widely used variational quantum eigensolver (VQE) algorithm for quantum chemistry by investigating the behavior of noisy ansatz circuits with numerical simulation. Using ansatz circuits derived from unitary coupled cluster (UCC) theory, we estimate the ground-state electronic energy of few-electron models to show how relative error and fidelity scale with levels of gate-based noise, inter-molecular configuration, ansatz depth, and optimization methods. We find ansatz depth is the leading indicator for fidelity and relative error, while error itself is robust to the level of theory and optimization method.