Regular Article

Impact of nonideal cycles on the efficiency of quantum heat engines^⋆

¹ Department of Physics, Sharif University of Technology, 14588 Tehran, Iran
² School of Physics, Institute for Research in Fundamental Sciences (IPM), 19395 Tehran, Iran
³ Department of Physics, University of Trieste, 34151 Trieste, Italy
⁴ National Institute for Nuclear Physics (INFN), Trieste Section, 34151 Trieste, Italy
⁵ Department of Mathematical, Physical, and Computer Sciences, University of Parma, 43124 Parma, Italy
⁶ National Institute for Nuclear Physics (INFN), Milan Bicocca Section, Parma Group, 43124 Parma, Italy

^a e-mail: benatti@ts.infn.it

Received: 26 September 2018
Revised: 22 March 2019
Published online: 18 July 2019

Abstract

Given a quantum heat engine that operates in a cycle that reaches maximal efficiency for a time-dependent Hamiltonian H(τ) of the working substance, with overall controllable driving H(τ) = g(τ) 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.