Entropy and information flow in quantum systems strongly coupled to baths

Considering von Neumann expression for reduced density matrix as thermodynamic entropy of a system strongly coupled to baths, we use nonequilibrium Green's function (NEGF) techniques to derive bath and energy resolved expressions for entropy, entropy production, and information flows. The consideration is consistent with dynamic (quantum transport) description and expressions reduce to expected forms in limiting cases of weak coupling or steady state. Formulation of the flows in terms of only system degrees freedom is convenient for simulation of thermodynamic characteristics of open nonequilibrium quantum systems. We utilize standard NEGF for derivations in noninteracting systems, Hubbard NEGF is used for interacting systems. Theoretical derivations are illustrated with numerical simulations within generic junction models.

Automated summary

By considering von Neumann expression and utilizing nonequilibrium Green's function techniques, the paper derived bath and energy resolved expressions for entropy, entropy production, and information flows. The formulation of these expressions in terms of system degrees freedom is convenient for simulating thermodynamic characteristics of open nonequilibrium quantum systems. Standard NEGF is used for noninteracting systems while Hubbard NEGF is employed for interacting systems in numerical simulations within generic junction models.