Quantum Otto heat engine based on a multiferroic chain working substance

TL;DR

This paper investigates a quantum Otto engine using a multiferroic chain, revealing how electric fields influence entanglement, chirality, and efficiency, with potential control over engine performance through external fields.

Contribution

It introduces a quantum Otto cycle based on a multiferroic chain, highlighting the role of electric fields in controlling entanglement and efficiency, which is a novel approach.

Findings

Efficiency saturates with increasing electric field.

Electric-field dependent threshold temperature affects pair entanglement.

Many-body entanglement is less sensitive to electric fields.

Abstract

We study a quantum Otto engine operating on the basis of a helical spin- 1/2 multiferroic chain with strongly coupled magnetic and ferroelectric order parameters. The presence of a finite spin chirality in the working substance enables steering of the cycle by an external electric field that couples to the electric polarization. We observe a direct connection between the chirality, the entanglement and the efficiency of the engine. An electric-field dependent threshold temperature is identified above which the pair correlations in the system, as quantified by the thermal entanglement, diminish. In contrast to the pair correlations, the collective many-body thermal entanglement is less sensitive to the electric field, and in the high temperature limit converges to a constant value. We also discuss the correlations between the threshold temperature of the pair entanglement, the spin chirality and the minimum of the fidelities in relation to the electric and magnetic fields. The efficiency of the quantum Otto cycle shows a saturation plateau with increasing electric field amplitude.