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

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 Landé 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 Landé factor and filling factors.