Robustness to spontaneous emission of a variational quantum algorithm

TL;DR

This paper investigates how spontaneous emission affects a variational quantum algorithm for combinatorial optimization, showing that the algorithm's variational nature naturally mitigates dissipation effects, with additional insights from an alternative optimization scheme.

Contribution

It demonstrates that variational quantum algorithms are inherently robust to spontaneous emission and explores an alternative optimization method using expected shortfall.

Findings

Dissipation effects are spontaneously attenuated by the variational process.

The variational algorithm maintains performance despite realistic dissipation.

An alternative optimization scheme using expected shortfall is proposed.

Abstract

We study theoretically the effects of dissipation on the performances of a variational quantum algorithm used to approximately solve a combinatorial optimization problem, the Maximum Independent Set, on a platform of neutral atoms. We take a realistic model of dissipation with spontaneous emission, and show numerically that the detrimental effects of these incoherent processes are spontaneously attenuated by the variational nature of the procedure. We furthermore implement an alternative optimization scheme recently proposed, where one uses the expected shortfall of the mean energy as the objective function.