ECAMP 15

Heat engines convert thermal energy into mechanical work and have been extensively studied in the classical and quantum regimes. In the quantum domain, however, nonclassical forms of energy exist, which are distinct from traditional heat and which can also be harnessed to generate work in cyclic engine protocols.

We introduce the concept of the Pauli engine: a novel quantum many-body engine powered by the energy difference between fermionic and bosonic ultracold particle ensembles, arising from the Pauli exclusion principle. The distinct quantum statistics lead to a redistribution of population across energy levels, enabling engine cycles that replace traditional heat strokes in the quantum Otto cycle. This concept has recently been realized experimentally in the BEC-BCS crossover regime [1].

Building on this idea, we also present several concepts for hybrid quantum-classical engines, where a change in quantum statistics is implemented either during the adiabatic work strokes or the isochoric heat strokes. While the Pauli engine alone demonstrated high efficiency, we show that combining quantum and classical effects can further enhance both efficiency and work output. All cycles are discussed in the context of ultracold atomic gases, which are well suited for their experimental realisation.

[1] J. Koch, K. Menon, E. Cuestas, S. Barbosa, E. Lutz, T. Fogarty, Th. Busch, A. Widera, Nature 621, 723 (2023).