Heidelberg 2015 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

Q: Fachverband Quantenoptik und Photonik

Q 19: Quantum Gases: Fermions III

Q 19.3: Talk

Tuesday, March 24, 2015, 11:30–11:45, K/HS2

Breakdown of quantized conductance with interacting ultracold fermions — •Martin Lebrat, Sebastian Krinner, Dominik Husmann, Charles Grenier, Jean-Philippe Brantut, and Tilman Esslinger — Institut für Quantenelektronik, ETH Zürich, Schweiz

We study the transport of ultracold fermions through a one-dimensional structure in the presence of strong attractive interparticle interactions. While conductance is quantized in steps of 1/h for weak interactions, as predicted by the Landauer-Büttiker theory of transport, this feature vanishes with increasing interactions.

Experimentally, we pinch off at its center an elongated cloud of ultracold ⁶Li atoms, effectively splitting it into two macroscopic reservoirs. The precise geometry of the junction is defined through a set of repulsive and attractive optical potentials, similarly to the gate potentials of an electronic quantum point contact. Upon inducing a population bias between the reservoirs, which can be addressed independently for different hyperfine species, a current sets in to restore thermal equilibrium. Measuring its magnitude for both spin states allows to access particle and spin conductance. Both show opposite behaviors as the atoms enter in the strong superfluid regime, delivering further insights on the breakdown of the quantized conductance.