On the contribution of work or heat in exchanged energy via interaction in open bipartite quantum systems

The question of with what we associate work and heat in a quantum thermodynamic process has been extensively discussed, mostly for systems with time-dependent Hamiltonians. In this paper, we aim to investigate the energy exchanged between two quantum systems through interaction where the Hamiltonian of the system is time-independent. An entropy-based re-definitions of heat and work are presented for these quantum thermodynamic systems therefore an entropy-based formalism of both the first and the second laws of thermodynamics are introduced. We will use the genuine reasoning based on which Clausius originally defined work and heat. The change in the energy which is accompanied by a change in the entropy is identified as heat, while any change in the energy which does not lead to a change in the entropy is known as work. It will be seen that quantum coherence does not allow all the energy exchanged between two quantum systems to be only of the heat form. Several examples will also be discussed. Finally, we will examine irreversibility from our entropy-based formalism of quantum thermodynamics.

Automated summary

This paper investigates the association between work and heat in a quantum thermodynamic process with a time-independent Hamiltonian. New definitions of heat and work based on entropy are introduced, and a formalism for the first and second laws of thermodynamics is established. The change in energy accompanied by a change in entropy is identified as heat, while energy changes without entropy changes are defined as work. It is found that quantum coherence prevents all the energy exchanged between two quantum systems from being in the form of heat. Several examples are discussed, and irreversibility is examined using the entropy-based formalism of quantum thermodynamics.