Open Quantum Matter-field Systems and Entropy

We consider a system of Fermions interacting with a coherent electromagnetic field and calculate the entropy dynamics. We obtain a negative term describing an entropy decrease depending on the electromagnetic field, which can cancel the positive term obtained according to the second law of thermodynamics. For the application of this theory to a semiconductor structure converting the environmental heat into coherent electromagnetic energy, we obtain a physical interpretation of the two processes, as field radiation by quantum transitions, and heat absorption by the Peltier effect.