Work

Universal efficiency boost in prethermal quantum heat engines at negative temperature

Year: 2025

Type: article

Abstract: Heat engines near the adiabatic limit typically assume a working medium at thermal equilibrium. However, quantum many-body systems often showcase conservation laws that hinder thermalization, leading to prethermalization in exotic stationary phases. This work explores whether prethermalization enhances or reduces engine efficiency. We investigate Otto cycles in quantum systems with varying numbers of conserved quantities. We find that additional conservation laws reduce efficiency at positive temperatures, but enhance it in regimes of negative temperatures. Our findings stem from general thermodynamic inequalities for infinitesimal cycles, and we provide evidence for integrable models undergoing finite cycles using the theoretical framework of Generalized Hydrodynamics. The relevance of our results for quantum simulators is also discussed.

Source: Nature Communications

DOI: 10.1038/s41467-025-66424-1

Authors: Alberto Brollo, Adolfo del Campo, Alvise Bastianello

Institutions: Technical University of Munich, University of Luxembourg, Donostia International Physics Center, Munich Center for Quantum Science and Technology

Language: English

Topic: Advanced Thermodynamics and Statistical Mechanics

Subfield: Statistical and Nonlinear Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $6,990

Funders: Deutsche Forschungsgemeinschaft, Fonds National de la Recherche Luxembourg