# Enhancement of efficiency in the Dicke model quantum heat engine

## TL;DR

This paper investigates a quantum heat engine based on the Dicke model, demonstrating efficiency enhancement near quantum phase transitions and analyzing the effects of model asymmetries.

## Contribution

It introduces a detailed analysis of efficiency improvements in a Dicke model quantum heat engine during a Stirling cycle, highlighting the role of quantum phase transitions and term balance.

## Key findings

- Efficiency peaks when coupling crosses critical values
- Maximum efficiency occurs with equal rotating and counter-rotating contributions
- Ground state degeneracy correlates with maximum efficiency

## Abstract

We analyze a quantum heat engine described by the full Dicke model. The system exhibit quantum phase transitions under certain conditions. We consider the system performing a Stirling thermodynamic cycle. We obtain an enhancement of efficiency when during the cycle the coupling parameter cross a critical value. We analyze the effect of unbalance between rotating and counter-rotating terms in the model. The maximum efficiency is obtained when the contributions of the counter-rotating and rotating terms are equal. The relation between ground state degeneracy, related to the quantum phase transition, and maximum efficiency is investigated.