Influences of counter-rotating wave terms on the trace distance of quantum states in the Rabi model
Wenwu Deng, Gao‐xiang Li · Journal of Physics B Atomic Molecular and Optical Physics · 2013
Based on a unitary transformation and a generalized rotating-wave approximation, the effect of the counter-rotating wave terms on the trace distance of quantum states for the qubit in the Rabi model is investigated. The analytical expressions of the eigenenergies and eigenstates of the qubit–field coupling system are obtained approximately. Starting from the two initial Bell states for the qubit and field, in which the qubit is in the same states, we find that the time evolution of the trace distance for the qubit states is only related to the difference between the populations in the qubit excited state but independent of the coherence of the qubit. The effect of the counter-rotating wave terms brings the trace distance of the quantum states of the qubit to exhibit fast oscillations in the strong coupling regime.