Estimating Franck-Condon factors using an NMR quantum processor

TL;DR

This paper presents a quantum computing method to estimate Franck-Condon factors, crucial for understanding molecular vibronic transitions, demonstrated experimentally with a three-qubit NMR quantum processor.

Contribution

It introduces a general quantum algorithm for estimating FCFs and experimentally validates it using NMR technology, combining translation operators and projection measurements.

Findings

Experimental FCF estimates agree with theoretical predictions.

Two measurement protocols successfully implemented on NMR quantum processor.

Method provides a new quantum approach to molecular spectroscopy analysis.

Abstract

Interaction of molecules with light may lead to electronic transitions and simultaneous vibrational excitations. Franck-Condon factors (FCFs) play an important role in quantifying the intensities of such vibronic transitions occurring during molecular photo-excitations. In this article, we describe a general method for estimating FCFs using a quantum information processor. The method involves the application of a translation operator followed by the measurement of certain projections. We also illustrate the method by experimentally estimating FCFs with the help of a three-qubit NMR quantum information processor. We describe two methods for the measurement of projections - (i) using diagonal tomography and (ii) using Moussa protocol. The experimental results agree fairly well with the theory.