Entanglement and causality in the interaction of the two-level atom with the field

The interaction between an initially pure two-level atom and the mixed thermal quantized field mode in the framework of the Jaynes–Cummings model is considered with the employment of quantum causal analysis . At the high temperature of the field, a distinction between the resulting properties of initially excited and ground atom states smoothes over and the whole state turns out to be causally asymmetric, entangled and 'classical' in the entropic sense. The average asymptotic entanglement is found. It is revealed that the thermalization acting on the field corresponds to the stronger causality and entanglement decay, rather than the thermalization acting only on the atom.