Finite-time performance of a single-ion quantum Otto engine

TL;DR

This paper analyzes the finite-time performance of a single-ion quantum Otto engine, revealing how stroke durations and residual coherence influence efficiency and inner friction.

Contribution

It introduces a detailed model of a quantum Otto engine with realistic finite-time strokes and explores how partial thermalization and residual coherence affect performance.

Findings

Partial thermalization can enhance efficiency due to residual coherence.

Faster expansion and compression increase inner friction and reduce efficiency.

Finite stroke durations significantly impact the engine's performance.

Abstract

We study how a quantum heat engine based on a single trapped ion performs in finite time. The always-on thermal environment acts like the hot bath, while the motional degree of freedom of the ion plays the role of the effective cold bath. The hot isochoric stroke is implemented via the interaction of the ion with its hot environment, while a projective measurement of the internal state of the ion is performed as an equivalent to the cold isochoric stroke. The expansion and compression strokes are implemented via suitable change in applied magnetic field. We study in detail how the finite duration of each stroke affects the engine performance. We show that partial thermalization can in fact enhance the efficiency of the engine, due to the residual coherence, whereas faster expansion and compression strokes increase the inner friction and therefore reduce the efficiency.