Effective thermodynamics of strongly coupled qubits

Interactions between a quantum system and its environment at low temperatures can lead to apparent violations of thermal laws for the system. The source of these violations is the coupling between the system and environment, which prevents the system from entering into a thermal state, a state of Gibbs form. On the other hand, for two-state systems, we show that one can define an effective temperature, placing the system into a pseudo-thermal state where effective thermal laws can be applied. We then numerically explore these assertions for an n-state environment inspired by the spin-boson environment.