There is an intimate connection of quantum thermodynamics with the theory of open quantum systems.
Quantum mechanics inserts dynamics into thermodynamics, giving a sound foundation to finite-time-thermodynamics.
The main assumption is that the entire world is a large closed system, and therefore, time evolution
is governed by a unitary transformation generated by a global Hamiltonian. For the combined system
bath scenario, the global Hamiltonian can be decomposed into:
where  is the system Hamiltonian,  is the bath Hamiltonian and  is the system-bath interaction.
The state of the system is obtained from a partial trace over the combined system and bath:
Reduced dynamics is an equivalent description of the system dynamics utilizing only system operators.
Assuming Markov property for the dynamics the basic equation of motion for an open quantum system is the Lindblad equation (GKLS):
 is a (Hermitian) Hamiltonian part and :
is the dissipative part describing implicitly through system operators  the influence of the bath on the system.
The Markov property imposes
that the system and bath are uncorrelated at all times .
The L-GKS equation is unidirectional and leads any initial state  to a steady state solution which is an invariant of the equation of motion .
The Heisenberg picture supplies a direct link to quantum thermodynamic observables. The dynamics of a system observable represented by the operator, , has the form:
where the possibility that the operator,  is explicitly time-dependent, is included.