Quantum Thermodynamics of Nanoscale Steady States Far from Equilibrium*

We develop a quantum thermodynamic description for nanoscale steady states that are sustained arbitrarily far from equilibrium by connecting with multiple reservoirs of different chemical potentials and temperatures. Our focus is to construct the steady-state thermodynamic function Φ_ss that accounts for irreversible processes of quantum kinetics. We identify and evaluate Φ_ss for the single bosonic or fermionic resonant level model in the wide-band limit, demonstrating that the nonequilibrium thermodynamic relations exactly produces the multiterminal, Landauer-Büttiker formula of charge, energy or heat currents beyond the linear response. The entropy production rate is also described accordingly. As the quantity Φ_ss is stationary in time, we can interpret it as the free entropy (or information) transferable by the steady state. The same nonequilibrium thermodynamic structure persists for a spin-degenerate single level with local interaction. Moreover, we show that the universal heat transport phenomena at low-temperatures exemplify how the function Φ_ss can characterize current fluctuations and the cumulant generating function.

Reference: N. Taniguchi, arXiv:1710.07385.