Quantum Optics Seminar: Professor Thomas Busch, Okinawa, Japan
Making statistics work: a quantum engine in the BEC-BCS crossover
Heat engines convert thermal energy into mechanical work and are well studied in the classical and in the quantum regimes. However, in the quantum realm genuine nonclassical forms of energy exist, different from heat, which can also be exploited in cyclic engines to produce useful work.
In this presentation I will introduce the concept of a Pauli engine, a novel quantum many-body engine fuelled by the energy difference between fermionic and bosonic ensembles of ultracold particles that follows from the Pauli exclusion principle. The difference in symmetry between these two systems leads to a change in the population distribution, which can be used to replace the traditional heat strokes in a quantum Otto engine.
I will also show that such a system has been realised by cycling the working medium of the engine between a Bose-Einstein condensate of bosonic molecules and a unitary Fermi gas (and back) through a magnetic field in a system of trapped superfluid 6Li atoms. The experiments obtain a work output of several 10^6 vibrational quanta per cycle with an efficiency of up to 25%, therefore establishing quantum statistics as a useful thermodynamic resource for work production.
Reference:
- Koch, K. Menon, E. Cuestas, S. Barbosa, E. Lutz, T. Fogarty, Th. Busch, A. Widera, Nature 621, 723 (2023).
- Menon, T. Fogarty, and Th. Busch, submitted (2025).