Quantum equation of motion for computing molecular excitation energies on a noisy quantum processor

TL;DR

This paper introduces a quantum equation of motion algorithm for calculating molecular excitation energies on noisy quantum processors, demonstrating its effectiveness on a LiH molecule using IBM Quantum hardware.

Contribution

It extends the classical equation of motion method to a quantum algorithm suitable for near-term noisy quantum computers, enabling efficient excitation energy calculations.

Findings

Successfully computed LiH excitation energies on a noisy quantum device.

Demonstrated the algorithm's efficiency and feasibility on current quantum hardware.

Provides a new approach for molecular simulations on near-term quantum computers.

Abstract

The computation of molecular excitation energies is essential for predicting photo-induced reactions of chemical and technological interest. While the classical computing resources needed for this task scale poorly, quantum algorithms emerge as promising alternatives. In particular, the extension of the variational quantum eigensolver algorithm to the computation of the excitation energies is an attractive option. However, there is currently a lack of such algorithms for correlated molecular systems that is amenable to near-term, noisy hardware. In this work, we propose an extension of the well-established classical equation of motion approach to a quantum algorithm for the calculation of molecular excitation energies on noisy quantum computers. In particular, we demonstrate the efficiency of this approach in the calculation of the excitation energies of the LiH molecule on an IBM Quantum computer.