Computing molecular excited states on a D-Wave quantum annealer

TL;DR

This paper demonstrates the use of a D-Wave quantum annealer to compute excited electronic states of molecules using TDHF and TDDFT methods within the Tamm-Dancoff approximation, showcasing potential for quantum chemistry applications.

Contribution

It introduces a novel application of a D-Wave quantum annealer for solving excited state eigenvalue problems in molecules, utilizing the Quantum Annealer Eigensolver (QAE).

Findings

Reproduces basis set convergence for H2 molecule

Calculates excited state properties like transition dipole moments

Computes potential energy profiles for NH3

Abstract

The possibility of using quantum computers for electronic structure calculations has opened up a promising avenue for computational chemistry. Towards this direction, numerous algorithmic advances have been made in the last five years. The potential of quantum annealers, which are the prototypes of adiabatic quantum computers, is yet to be fully explored. In this work, we demonstrate the use of a D-Wave quantum annealer for the calculation of excited electronic states of molecular systems. These simulations play an important role in a number of areas, such as photovoltaics, semiconductor technology and nanoscience. The excited states are treated using two methods, time-dependent Hartree-Fock (TDHF) and time-dependent density-functional theory (TDDFT), both within a commonly used Tamm-Dancoff approximation (TDA). The resulting TDA eigenvalue equations are solved on a D-Wave quantum annealer using the Quantum Annealer Eigensolver (QAE), developed previously. The method is shown to reproduce a typical basis set convergence on the example H$_2$ molecule and is also applied to several other molecular species. Characteristic properties such as transition dipole moments and oscillator strengths are computed as well. Three potential energy profiles for excited states are computed for NH$_3$ as a function of the molecular geometry. Similar to previous studies, the accuracy of the method is dependent on the accuracy of the intermediate meta-heuristic software called qbsolv.