Auger Spectroscopy via Generative Quantum Eigensolver: A Quantum Approach to Molecular Excitations

TL;DR

This paper introduces a hybrid quantum-classical workflow utilizing a generative quantum eigensolver to accurately compute Auger spectra, demonstrating its effectiveness on water and highlighting advantages over classical methods.

Contribution

The work presents a novel quantum approach combining GQE and quantum EOM methods for calculating Auger spectra, enabling scalable and efficient simulations of molecular electronic structures.

Findings

Successfully calculated water's Auger spectrum with good agreement to classical and experimental data.

GQE-based ground state estimation reduces gate count compared to VQE.

Workflow benefits from HPC and GPU acceleration for larger systems.

Abstract

Auger electron spectroscopy, a way of characterizing electronic structure through core-level decay processes, is widely used in materials characterization; however direct calculation from molecular geometry requires accurate treatment of many excited states, posing a challenge for classical methods. We present a hybrid quantum-classical workflow for calculating Auger spectra that combines the generative quantum eigensolver (GQE) for ground-state preparation, the quantum self-consistent equation-of-motion method for excited-state calculations, and the one-centre approximation for Auger transition rates. GQE uses a GPT-2 model to generate quantum circuits for ground-state optimization, allowing our workflow to benefit from HPC parallelization and GPU-acceleration for favourable scaling with system size. We demonstrate the validity of our workflow by calculating the Auger spectrum of water with the STO-3G basis set and demonstrating qualitative and quantitative agreement with spectra obtained using completely classical full configuration interaction calculations, from the computational literature, and from the experimental literature. We also find that for water, substituting the variational quantum eigensolver (VQE) for GQE results in near-identical spectra, but that the ground state estimator generated by GQE contains about half the total gate count as that generated by VQE.