The multilevel four-stroke swap engine and its environment

Raam Uzdin*, Ronnie Kosloff

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


A multilevel four-stroke engine where the thermalization strokes are generated by unitary collisions with thermal bath particles is analyzed. Our model is solvable even when the engine operates far from thermal equilibrium and in the strong system-bath coupling. Necessary operation conditions for the heat machine to perform as an engine or a refrigerator are derived. We relate the work and efficiency of the device to local and non-local statistical properties of the baths (purity, index of coincidence, etc) and put upper bounds on these quantities. Finally, in the ultra-hot regime, we analytically optimize the work and find a striking similarity to results obtained for efficiency at maximal power of classical engines. The complete swap limit of our results holds for any four-stroke quantum Otto engine that is coupled to the baths for periods that are significantly longer than the thermal relaxation time.

Original languageAmerican English
Article number095003
JournalNew Journal of Physics
StatePublished - 12 Sep 2014

Bibliographical note

Publisher Copyright:
© 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.


  • Otto engine
  • heat engine
  • multilevel
  • quantum thermodynamics


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