Simulating Energy Transfer in Molecular Systems with Digital Quantum Computers

TL;DR

This paper demonstrates how hybrid quantum-classical methods can simulate energy transfer in molecular systems, showing promising results and error mitigation techniques on current quantum hardware.

Contribution

It introduces a multi-scale workflow combining molecular dynamics, quantum chemistry, and hybrid quantum algorithms for simulating exciton dynamics in molecules.

Findings

Feasibility shown for simulating exciton dynamics on quantum computers

Quantum simulations qualitatively match expected behaviors

Error mitigation significantly improves simulation accuracy

Abstract

Quantum computers have the potential to simulate chemical systems beyond the capability of classical computers. Recent developments in hybrid quantum-classical approaches enable the determinations of the ground or low energy states of molecular systems. Here, we extend near-term quantum simulations of chemistry to time-dependent processes by simulating energy transfer in organic semiconducting molecules. We developed a multi-scale modeling workflow that combines conventional molecular dynamics and quantum chemistry simulations with hybrid variational quantum algorithm to compute the exciton dynamics in both the single excitation subspace (i.e. Frenkel Hamiltonian) and the full-Hilbert space (i.e. multi-exciton) regimes. Our numerical examples demonstrate the feasibility of our approach, and simulations on IBM Q devices capture the qualitative behaviors of exciton dynamics, but with considerable errors. We present an error mitigation technique that combines experimental results from the variational and Trotter algorithms, and obtain significantly improved quantum dynamics. Our approach opens up new opportunities for modeling quantum dynamics in chemical, biological and material systems with quantum computers.