Macroscopic quantum states, quantum phase transition for $N$ three-level atoms in an optical cavity -- Gauge principle and non-Hermitian Hamiltonian

Ni Liu, Xinyu Jia, J. -Q. Liang

We study in this paper the quantum phase transition (QPT) from normal phase (NP) to superradiant phase (SP) for $N$ three-level atoms in a single-mode optical cavity for both Hermi…