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Q: Fachverband Quantenoptik und Photonik

Q 35: Quantum Gases (Fermions) I

Q 35.1: Gruppenbericht

Mittwoch, 13. März 2019, 14:00–14:30, S HS 037 Informatik

Beyond particle transport at an atomic quantum point contact: thermoelectric effects and spin control — Martin Lebrat, •Philipp Fabritius, Samuel Häusler, Dominik Husmann, Jeff Mohan, Tilman Esslinger, and Laura Corman — Departmen of Physics, ETH Zurich, 8093 Zurich, Switzerland

In this talk, we report on a few remarkable transport properties of lithium-6 atoms through a quantum point contact (QPC) precisely defined by a set of optical potentials. The versatility of cold-atom techniques allows us to directly measure heat or spin currents and to tune interatomic interactions.

In a first experiment performed with a unitary Fermi gas close to the superfluid transition, we probe the thermoelectric effects induced by a temperature difference accross the QPC. We show that the system evolves towards a non-equilibrium steady state, associated with a reduced heat diffusion and a strong violation of the Wiedemann-Franz law. In a second experiment performed with weakly interacting atoms, we locally lift the spin degeneracy of atoms inside the QPC using an optical tweezer tuned very close to atomic resonance. We observe quantized, spin-polarized transport that is robust to dissipation and sensitive to interaction effects on the scale of the Fermi length.

These results open the way to the quantum simulation of efficient thermoelectric and spintronic devices with cold atoms.