Interplay of quantum phase transition and flat band in hybrid lattices

TL;DR

This paper explores how superradiant phase transition influences flat band localization in a hybrid lattice system, revealing a periodic critical region and linking flat band physics with quantum phase transitions.

Contribution

It introduces a novel connection between superradiant phase transition and flat band physics in a Dicke-Hubbard lattice, expanding understanding of many-body and quantum optics phenomena.

Findings

Critical region varies periodically with wavenumber k.

Flat band and localization are controllable via the ground-state SPT.

Establishes a fundamental link between flat band physics and superradiant phase transition.

Abstract

We investigate the interplay of superradiant phase transition (SPT) and energy band physics in an extended Dicke-Hubbard lattice whose unit cell consists of a Dicke model coupled to an atomless cavity. We found in such a periodic lattice the critical point that occurs in a single Dicke model becomes a critical region that is periodically changing with the wavenumber $k$. In the weak-coupling normal phase of the system we observed a flat band and its corresponding localization that can be controlled by the ground-state SPT. Our work builds the connection between flat band physics and SPT, which may fundamentally broaden the regimes of many-body theory and quantum optics.