A Thermodynamic Framework for Coherently Driven Systems

TL;DR

This paper develops a new thermodynamic framework for coherently driven quantum systems at the nanoscale, revealing a stricter second law that relates output light noise to input noise, and illustrating its implications with models like the three-level maser.

Contribution

It introduces a thermodynamic framework for coherently driven systems that accounts for quantum effects and output light noise, extending traditional thermodynamics to the nanoscale.

Findings

The second law is tighter for coherently driven systems, constraining output light noise.

The three-level maser can be viewed as a noise-reducing engine.

The framework applies to various driven-dissipative quantum models.

Abstract

The laws of thermodynamics are a cornerstone of physics. At the nanoscale, where fluctuations and quantum effects matter, there is no unique thermodynamic framework because thermodynamic quantities such as heat and work depend on the accessibility of the degrees of freedom. We derive a thermodynamic framework for coherently driven systems, where the output light is assumed to be accessible. The resulting second law of thermodynamics is strictly tighter than the conventional one and it demands the output light to be more noisy than the input light. We illustrate our framework across several well-established models and we show how the three-level maser can be understood as an engine that reduces the noise of a coherent drive. Our framework opens a new avenue for investigating the noise properties of driven-dissipative quantum systems.