Comment on "Nonequilibrium dynamics of superconductivity in the attractive Hubbard model"

TL;DR

This paper comments on recent numerical studies of nonequilibrium superconductivity in the attractive Hubbard model, clarifying misconceptions about the origin of observed instabilities and emphasizing the need for further verification.

Contribution

It critically analyzes prior interpretations of spatial instabilities post-quench, highlighting inaccuracies and proposing directions for future research.

Findings

The observed inhomogeneities are not solely due to large final coupling U_f.

Further numerical work is needed to confirm the instability mechanism.

Clarification of the nature of the steady state post-quench.

Abstract

In a recent preprint [arXiv:1803.04118v2] Chern and Barros report numerical simulations of the mean-field interaction quench dynamics, $U_i\to U_f$, of the attractive Hubbard model that confirm our earlier prediction [Europhys. Lett. 85, 20004 (2008), arXiv:0805.2798] of spontaneous eruption of spatial inhomogeneities in the post-quench state with periodically oscillating superconducting order. Chern and Barros attribute this instability with respect to spatial fluctuations to the large magnitude of the final Hubbard coupling $U_f$. We point out that this interpretation is inaccurate and discuss further work necessary to numerically verify the mechanism of the instability and the nature of the steady state.