Comment on "Exploring chaos in the Dicke model using ground-state fidelity and the Loschmidt echo"

TL;DR

This paper critiques a previous study on the Dicke model, clarifying that the observed fidelity jumps are due to symmetry considerations rather than chaos, thus refining the understanding of phase transitions in the model.

Contribution

It corrects the interpretation of fidelity jumps in the Dicke model by emphasizing the importance of symmetry, challenging prior claims linking them to chaos.

Findings

Fidelity jumps are due to symmetry, not chaos

Parity symmetry accounts for the observed numerical features

Previous chaos-related interpretations are invalidated

Abstract

In [PRE \textbf{90}, 022920 (2014), arXiv:1404.6738] a study of the ground state fidelity of the Dicke model as a function of the coupling parameter is presented. Abrupt jumps of the fidelity in the superradiant phase are observed and are assumed to be related to the transition to chaos. We show that this conclusion results from a misinterpretation of the numerics. In fact, if the parity symmetry is taken into account, the unexpected jumps disappear.