Superradiant Quantum Phase transition for Landau Polaritons with Rashba and Zeeman couplings

TL;DR

This paper develops a theoretical framework for cavity quantum electrodynamics in a 2D electron gas with Rashba and Zeeman couplings, revealing conditions for superradiant quantum phase transitions influenced by Landau level crossings.

Contribution

It introduces a comprehensive theory showing how Rashba and Zeeman couplings can induce superradiant phase transitions in 2D electron gases within cavity QED systems.

Findings

Superradiant phase transition can occur via pure in-plane Zeeman coupling under ideal conditions.

Landau level crossings induced by Rashba coupling promote the superradiant phase transition.

Realistic conditions require fine tuning of parameters for the phase transition to occur.

Abstract

We develop a theory of cavity quantum electrodynamics for a two-dimensional electron gas in the presence of Rashba spin-orbit and Zeeman couplings and perpendicular magnetic field, coupled to a spatially nonuniform quantum photon field. We show that the superradiant quantum phase transition (SQPT), also known as photon condensation, can in principle occur through a pure in-plane Zeeman coupling, but it requires extremely small (unrealistic) quantum well widths or extremely fine tuning of the effective Land\'e factor which makes two Landau levels coincide. Landau level crossings can also be induced by the Rashba spin-orbit coupling and they promote the SQPT which can be obtained for certain values of the effective Land\'e factor and filling factors.