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Q: Fachverband Quantenoptik und Photonik

Q 22: Posters: Quantum Optics and Photonics II

Q 22.58: Poster

Dienstag, 10. März 2020, 16:30–18:30, Empore Lichthof

Thermoelectric transport properties of an ultracold Fermi gas — •Philipp Fabritius, Samuel Häusler, Martin Lebrat, Jeff Mohan, Laura Corman, and Tilman Esslinger — Department of Physics, ETH Zurich, 8093 Zurich, Switzerland

On this poster we present a comparison between the thermoelectric transport properties of a non-interacting Fermi gas and a unitary Fermi gas flowing through a quasi two-dimensional channel or a quantum point contact (QPC. In a first experiment we probe the thermoelectric effects induced by a temperature difference across the QPC by measuring the evolution of temperature and particle number in the reservoirs. The transport properties of channel and reservoir can be changed individually via a attractive gate beam and a narrowly focused, repulsive wall beam which changes the zero mode energy of the channel. These two tuning knobs allow to change the particle flow from hot-to-cold to cold-to-hot. This corresponds to tuning the effective Seebeck coefficient. In another experiment we probed the thermoelectric properties of a unitary Fermi gas close to the superfluid transition flowing through a QPC. Here we found that the Lorentz number does not agree with the value given by the Wiedemann-Frantz law which indicates non-Fermi liquid behavior, while the measured, non-zero Seebeck coefficient is not expected for a superfluid. Together this leads to a greatly enhanced thermoelectric efficiency. These results and recent experiments implementing local spin-filter open the way to study systems where not only heat- and particle transport is coupled but also spin.