The second quantum revolution has witnessed a rediscovery and re-evaluation of fundamental quantum properties, and a concomitant evolution towards technological applications that has propelled an exponential improvement of experimental techniques at the nanoscale.

As these technologies have become closer to market, the community is faced with considerations over “beyond-decoherence” thermal effects, entropy, and power consumption. Therefore, the understanding of thermodynamic laws at the level of small and coherently driven quantum systems has become important.

This has spawned quantum thermodynamics [1], a field that aims to expand the well-established laws of thermodynamics to small quantum systems that cannot be described by the so-called thermodynamic limit. Quantum thermodynamics extends the concepts of heat, work, and entropy to few-particle quantum systems. Its formalism includes additional quantities such as quantum coherence and entanglement, which may affect the behaviour of small quantum systems and can lead, for example, to novel concepts or resources for thermodynamics machines. In addition, actual quantum technology devices necessitate a description at finite temperature, whereas, usually, their protocols correspond to non-adiabatic out-of-equilibrium regimes. Understanding these devices implies the development of related finite-time, out-of-equilibrium quantum thermodynamic formalisms.

In small quantum systems, many-body interactions may have particularly dramatic effects. This research direction is recent and has already led to promising results indicating that many-body effects may constitute a clear advantage for operating nanoscale devices [2-4]: they may drive or destroy desirable entanglement and quantum coherence within the system; they may be responsible for quantum phase transitions [5]; they may lead to the destruction of quantum coherence through entanglement of the quantum system with the environment; their strength may determine the level of memory in the interaction between the system and its bath; they may control localization versus diffusive / transport when combined with disorder [6];  they may also affect the dynamical regime of a system, for example with respect to how close it is to adiabaticity [7]. Many questions remain with respect to the effects of many-body interactions on quantum thermodynamics. A better understanding would be welcome on issues such as, e.g., the role of many-body interactions for quantum particles driven out of equilibrium, and how these affect quantum thermodynamical quantities, i.e., do they contribute or oppose reversibility and thermalisation? Also, are there signatures of many-body interactions in thermodynamic distributions, for example across quantum phase transitions? Do these effects depend on the system size? Can one engineer many-body interactions to improve quantum machine efficiency [8]? How can one probe a many-body quantum fluid to measure the work obtained from a thermodynamic protocol? How does one adapt many-body techniques to calculate cumbersome quantum thermodynamics properties [9]? In this mini-colloquium we will review recent advances in quantum thermodynamics with a particular emphasis on the effects of many-body interactions.

References

[1] See e.g. : R. Alicki and R. Kosloff, Introduction to Quantum Thermodynamics: History and Prospects (Springer, Cham, Switzerland, 2018), pp. 1–33.

[2] J. Jaramillo, M. Beau and A. del Campo, “Quantum supremacy of many-particle thermal machines”, New J. Phys. 18, 075019 (2016).

[3] W. Niedenzu and G. Kurizki, “Cooperative many-body enhancement of quantum thermal machine”, New J. Phys. 20, 113038 (2018).

[4] T. Chen and D. Poletti, “Thermodynamic performance of a periodically driven harmonic oscillator correlated with the baths”, Phys. Rev. E 104, 054118 (2021).

[5] J. Hubbard, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences. 276 (1365): 238–257 (1963).

[6] C. Chiaracane, M. T. Mitchison, A. Purkayastha, G. Haack, and J. Goold, “Quasiperiodic quantum heat engines with a mobility edge”,  Phys. Rev. Research 2, 013093 (2020).

[7] A.H. Skelt, I. D'Amico, “Characterizing Adiabaticity in Quantum Many-Body Systems at Finite Temperature”, Ad. Q. Tech. 3, 1900139 (2020). 

[8] V. Mukherjee and U. Divakaran, “Many-body quantum thermal machines”, J. Phys. Condens. Matter 33, 454001 (2021).

[9] M. Herrera, R. M. Serra & I. D’Amico, “DFT-inspired methods for quantum thermodynamics”, Scientific Reports volume 7, 4655 (2017).