Modulation-based superradiant phase transition in the strong-coupling regime

The Dicke model can exhibit quantum phase transition between the normal and superradiant phases when strength of light-matter coupling exceeds ultrastrong-coupling regime. However, it is challenging to observe this in practical systems due limited or finite two-photon ${A}^{2}$ terms. Here we show that by applying a periodic modulation frequency two-level standard strong-coupling regime, an anisotropic with tunable rotating counter-rotating terms regime be achieved. We calculate ground state excitation spectrum parameters. Our result shows observed cavity- circuit-quantum electrodynamics strong coupling.