Superradiant Transition to a Fermionic Quasicrystal in a Cavity

TL;DR

This paper investigates a superradiant transition in a one-dimensional fermionic gas within a cavity, revealing a first-order transition influenced by an incommensurate lattice and a unique density-dependent mechanism that confirms the fermionic quasicrystal superradiance.

Contribution

It introduces a novel first-order Dicke transition mechanism driven by indirect resonance effects in fermionic gases with incommensurate lattices.

Findings

Identification of a first-order Dicke transition induced by indirect resonance.

Critical pumping strength exhibits a linear V-shape near a specific filling.

Verification of the fermionic nature through density-dependent superradiant transition.

Abstract

Recently, the steady state superradiance in degenerate Fermi gases has been realized in a cavity, following the previous discovery of the Dicke transition in Bose gases. The most prominent signature of fermionic Dicke transition is its density dependence, which is manifested as the Fermi surface nesting effect and the Pauli blocking effect. We study the superradiant transition in one-dimensional Fermi gases in a cavity with the presence of an incommensurate dipolar lattice. We find a first-order Dicke transition induced by indirect resonance effect, which is a resonance between two atomic levels by the level repulsion from a third level, and causes extra gap opening. By formulating a phenomenological theory, we find that the critical pumping strength for this first-order Dicke transition shows a linear V-shape kink near a particular indirect resonance modified filling $\nu_{\rm IRM}$. The presence and the unique density dependence of this transition manifest the fermionic nature and verify the mechanism of the quasicrystal superradiant transition.