Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 51: Poster: Quantum Optics and Photonics IV

Q 51.22: Poster

Wednesday, March 7, 2018, 16:15–18:15, Redoutensaal

Bridging the thermoelectric and superfluid fountain effects with ultracold fermions — •Martin Lebrat, Dominik Husmann, Samuel Häusler, Philipp Fabritius, Laura Corman, Jean-Philippe Brantut, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, 8093 Zürich, Switzerland

An out-of-equilibrium system with temperature and chemical potential gradients needs both heat and matter currents to relax to thermodynamical equilibrium. The relaxation dynamics illuminates the microscopic mechanisms responsible for transport and energy conversion between heat and work, which is of great technological importance for cooling (Peltier effect) or power generation (Seebeck effect).

Using two reservoirs of fermionic lithium-6 atoms connected by an optically-shaped constriction, we demonstrate such thermoelectric effects and investigate the influence of interactions and constriction properties. With weak interactions and a 2D constriction, thermoelectric coupling can be optimized by controlling the geometry or introducing disorder [1]. With strongly interacting fermions close to the superfluid transition and a quasi-1D constriction, the system evolves towards a non-equilibrium steady state, associated with a reduced heat diffusion and a strong violation of the Wiedemann-Franz law. Measuring thermoelectric transport coefficients as a function of constriction anisotropy and degeneracy, we underline the analogies and differences between our observations and the celebrated fountain effect shown with superfluid helium-4.   

[1] J.-P. Brantut et al., Science 342, 713 (2013)