Current fluctuations in quantum absorption refrigerators

TL;DR

This paper analyzes the full statistical fluctuations of heat transfer in a quantum absorption refrigerator, providing analytical tools to optimize nanoscale cooling devices beyond average performance metrics.

Contribution

It introduces a method to compute the full counting statistics of heat exchange in a three-level quantum refrigerator, extending beyond average current analysis.

Findings

Derived the complete cumulant generating function for heat exchange.

Provided closed-form expressions for average cooling current and noise.

Validated results through analytical derivations and simulations.

Abstract

Absorption refrigerators transfer thermal energy from a cold bath to a hot bath without input power by utilizing heat from an additional "work" reservoir. Particularly interesting is a three-level design for a quantum absorption refrigerator, which can be optimized to reach the maximal (Carnot) cooling efficiency. Previous studies of three-level chillers focused on the behavior of the averaged cooling current. Here, we go beyond that and study the full counting statistics of heat exchange in a three-level chiller model. We explain how to obtain the complete cumulant generating function of the refrigerator in steady state, then derive a partial cumulant generating function, which yields closed-form expressions for both the averaged cooling current and its noise. Our analytical results and simulations are beneficial for the design of nanoscale engines and cooling systems far from equilibrium, with their performance optimized according to different criteria, efficiency, power, fluctuations and dissipation.