TWO-PHOTON ABSORPTION AND EMISSION PROCESS
Franco Fagnola, Roberto Quezada · Infinite Dimensional Analysis Quantum Probability and Related Topics · 2005
We analyze the two-photon absorption and emission process and characterize the stationary states at zero and positive temperature. We show that entangled stationary states exist only at zero temperature and, at positive temperature, there exists infinitely many commuting invariant states satisfying the detailed balance condition.