Impact of nonideal cycles on the efficiency of quantum heat engines

TL;DR

This paper investigates how nonideal, time-independent perturbations affect the efficiency of quantum heat engines, demonstrating that optimality can be maintained up to third-order deviations with proper tuning.

Contribution

It introduces a method to suppress efficiency deviations in quantum heat engines under perturbations by tuning interactions in a two-qubit system.

Findings

Efficiency deviation can be suppressed up to third order in perturbation.

Proper tuning of interactions maintains near-optimal engine performance.

The approach applies to systems with two two-level subsystems.

Abstract

Given a quantum heat engine that operates in a cycle that reaches maximal efficiency for a time-dependent Hamiltonian H(t) of the working substance, with overall controllable driving H(t) = g(t) H, we study the deviation of the efficiency from the optimal value due to a generic time-independent perturbation in the Hamiltonian. We show that for a working substance consisting of two two-level systems, by suitably tuning the interaction, the deviation can be suppressed up to the third order in the perturbation parameter-and thus almost retaining the optimality of the engine.