The study of out-of-equilibrium quantum thermodynamics has received a significant thrust thanks to the experimental advances in the control and manipulation of microscopic systems. Work, heat and entropy, ubiquitous concepts in traditional thermodynamics, assume in this context the role of stochastic variables. Their fluctuations can be ingeniously related, through fluctuation theorems, to equilibrium properties, as is the case of the celebrated Jarzynski equality. In the first part of this seminar, I will revise these concepts and discuss experimental schemes and realisations to directly measure work, heat and entropy in quantum systems [1-3].

In the second part, I will present designs of small quantum thermal machines using only a few qubits. This is the ideal context to investigate the effects of quantum correlations, for example entanglement and discord, on the performance of such quantum engines [4-6].

References:

[1] L. Mazzola, G. De Chiara, M. Paternostro, PRL 110, 230602 (2013)

[2] T. Batalhão et al. (De Chiara), PRL 113, 140601 (2014)

[3] M. Brunelli et al. (De Chiara), PRL 121, 160604 (2018)

[4] A. Hewgill, A. Ferraro, G. De Chiara, Phys. Rev. A 98, 042102 (2018)

[5] A. Hewgill et al. (De Chiara), Phys. Rev. E 101, 012109 (2020)

[6] G. De Chiara and M. Antezza, Phys. Rev. Res. 2, 033315 (2020).