Bridging Quantum and Semi-Classical Thermodynamics in Cavity QED

TL;DR

This paper explores the connection between quantum and semi-classical thermodynamics in cavity QED, revealing how different frameworks affect thermodynamic uncertainty relations and system behavior.

Contribution

It formulates a rigorous semi-classical limit of cavity QED and compares the resulting thermodynamic descriptions with the fully quantum model.

Findings

Semi-classical limit can qualitatively differ from quantum model

Violations of thermodynamic uncertainty relations are framework-dependent

Power source treatment restores uncertainty relation violations in semi-classical limit

Abstract

In cavity quantum electrodynamics (QED), photons leaving the cavity can be irreversibly lost or reused as a power source. This dichotomy is reflected in two different thermodynamic bookkeepings of the light field, both corresponding to valid thermodynamic frameworks. In this work, we formulate a rigorous semi-classical limit of cavity QED and show that the resulting thermodynamic description may qualitatively differ from that of the fully quantised model. We find that violations of the thermodynamic uncertainty relations are recovered in the semi-classical limit only by one of the two thermodynamic frameworks: the one which treats part of the photon flux as a power source. We illustrate our findings in a three-level system coupled to a driven cavity.