Hannover 2016 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 58: Poster: Quantum Optics and Photonics IV

Q 58.65: Poster

Donnerstag, 3. März 2016, 16:30–19:00, Empore Lichthof

Connecting strongly correlated superfluids by a quantum point contact — •Martin Lebrat¹, Samuel Häusler¹, Dominik Husmann¹, Sebastian Krinner¹, Jean-Philippe Brantut¹, Shun Uchino², Thierry Giamarchi³, and Tilman Esslinger¹ — ¹Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland — ²Center for Emergent Matter Science, RIKEN, Saitama 351-0198, Japan — ³Department of Quantum Matter Physics, University of Geneva, 1211 Geneva, Switzerland

We study strongly interacting Fermi gases connected by a tunable, ballistic constriction and measure a non-linear current-bias relation, reminescent of superconducting weak links. We prepare an elongated cloud of ultracold ⁶Li at unitarity by tuning its scattering length close to a Feshbach resonance. The cloud is then pinched off at its center using repulsive laser beams, effectively splitting it into two macroscopic reservoirs connected by a one-dimensional constriction, a quantum point contact (QPC).

By imposing an atom number imbalance between the two clouds and observing the dynamics of particle flow, we analyse the current-bias characteristics of our system and find nonlinear behaviour indicating superfluid behaviour. The results agree quantitatively with a biased superfluid point contact model treated with the Keldysh formalism, suggesting that the supercurrent originates from multiple Andreev reflections. We study how the current-bias characteristics depend on the density in the QPC and finite temperature.