Quantum Heat Engines and Refrigerators
Dr. Michele Campisi (Department of Physics and Astronomy, University of Florence, Italy)

I will begin showing that heat engines and refrigerators can be understood as a driven bipartite quantum system. I will then illustrate that a fluctuation theorem (the so called heat engine fluctuation relation or HEFR) holds for such system [1]. Fluctuation theorems are exact relations in non-equilibrium thermodynamics that are obeyed by the statistics of work and heat (which are indeed stochastic variables) [2]. The second law of thermodynamics in both Carnot and Kelvin formulation can be quickly derived from the HEFR, and as well in the formulation according to which heat spontaneously flows from hot to cold. I will then illustrate a possible experimental realisation of quantum heat engine/refrigerator with superconducting qubits, and illustrate its functioning [3].
If time will allow I will discuss how quantum measurements and feedback control may break the HEFR and illustrate the possible implementation a Maxwell Demon that can steer energy from cold reservoir to a hot one by observing the state of a central qubit playing the role of “trapdoor” and using the acquired information [4].

[1] M. Campisi Fluctuation relation for quantum heat engines and refrigerators, J. Phys A: Math Theor 47, 245001 (2014)
[2] M. Campisi, P. Hänggi, and P. Talkner, Colloquium. Quantum Fluctuation Relations: Foundations and Applications, Rev. Mod. Phys. 83 , 771 (2011)
[3] M. Campisi, J. Pekola, R. Fazio, Nonequilibrium fluctuations in quantum heat engines: Theory, example, and possible solid state experiments, New J. Phys.17 0350 (2015)
[4] M. Campisi, J. Pekola and R. Fazio, Feedback controlled heat transport in quantum devices: Theory and solid state experimental proposal, New J. Phys. 19 05302 (2017)