Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 7: Quantengase: Fermionen

Q 7.3: Vortrag

Montag, 12. März 2012, 14:30–14:45, V47.02

Conduction of ultracold Fermions through a mesoscopic channel — •David Stadler, Jean-Philippe Brantut, Jakob Meineke, Sebastian Krinner, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zürich, 8093 Zürich, Switzerland

We present a measurement of ultracold Fermions flowing through a horizontally oriented quasi 2-dimensional constriction which is connected to two macroscopic atom reservoirs. The constriction is made by a blue detuned laser beam that has a TEM01 mode, where atoms can only stay in a thin region of about 500nm between the two intensity maxima. A controlled imbalance of the number of atoms in the two reservoirs induces then a current of atoms from one side to the other. We observe the current of atoms as a function of time and see a characteristic decay of the atom number imbalance to its equilibrium position with equal atom number in both reservoirs. Secondly, we image the central part between the reservoirs where the 2-dimensional constriction is located. With our high-resolution imaging system we are able to measure in-situ the density distribution of atoms in the presence of a current. This gives us insight into the physical mechanisms that take place in the constriction and at the contacts to the reservoirs. We investigated the current of atoms in two very different situations. One is ballistic flow where we only have the quasi 2-dimensional constriction and the other is diffusive flow. Eventhough the macroscopic current of atoms is the same, we see a very different local behaviour of the atomic density in the constriciton and at the contacts.