Power fluctuations in a finite-time quantum Carnot engine

TL;DR

This paper investigates how the finite Hilbert space structure of a quantum Carnot engine affects its stability and fluctuations, demonstrating potential for high-performance, stable quantum heat engines surpassing simpler models.

Contribution

It introduces a finite-time quantum Carnot engine model based on a degenerate multilevel system and analyzes how degeneracy and level number optimize stability and performance.

Findings

Optimal degeneracy improves engine stability.

Engine performance can surpass nondegenerate two-level systems.

High stability and performance are achievable in cyclic quantum heat engines.

Abstract

Stability is an important property of small thermal machines with fluctuating power output. We here consider a finite-time quantum Carnot engine based on a degenerate multilevel system and study the influence of its finite Hilbert space structure on its stability. We optimize in particular its relative work fluctuations with respect to level degeneracy and level number. We find that its optimal performance may surpass those of nondegenerate two-level engines or harmonic oscillator motors. Our results show how to realize high-performance, high-stability cyclic quantum heat engines.