Positivity of entropy production for the three-level maser

TL;DR

This paper demonstrates that correcting for detuning in the energy levels of a three-level maser ensures positive entropy production, clarifying thermodynamic consistency in optical transition analysis.

Contribution

It introduces a correction method for detuning effects that guarantees positive entropy production in the three-level maser model.

Findings

Proper detuning corrections restore positive entropy production.

The method applies broadly to optical transitions with detuned light modes.

Clarifies thermodynamic analysis of quantum optical systems.

Abstract

Entropy production is a key concept of thermodynamics and allows one to analyze the operation of engines. For the Scovil-Schulz-DuBois heat engine, the archetypal three-level thermal maser coupled to thermal baths, it was argued that the common definition of heat flow may provide negative entropy production for certain parameters [E. Boukobza and D. J. Tannor, Phys. Rev. Lett. 98, 240601 (2007)]. Here, we show that this can be cured, if corrections for detuning are properly applied to the energies used for the bath transitions. This method can be used more generally for the thermodynamical analysis of optical transitions where the modes of the light field are detuned from the transition energy.