Controlling and probing superfluid transport through an atomic quantum point contact

We report on the control of the superfluid transport of a strongly interacting Fermi gas flowing through a quasi-two-dimensional contact and through a quantum point contact (QPC). Using shaped light we can create almost arbitrary potential landscapes for the atoms as well as effective magnetic fields and dissipation channels to alter and probe their transport. Taking multiple absorption pictures also allows us to directly measure particle, heat and spin currents. When introducing strong interactions in fermionic Lithium-6 we find that the thermoelectric effects induced by a temperature difference across a two-dimensional channel can be tuned using an attractive as well as a repulsive gate to change the relative strength of channel and reservoir contributions. Thus changing the particle transport going from hot to cold to going from cold to hot. We find that the strong interactions reduce the Seebeck coefficient of the channel which we attribute to hydrodynamic effects and resulting superfluid correlations inside the channel. We also introduce a spin selective dissipation via an optical tweezer inside a QPC. The dissipation has a strong effect on the transport of the superfluid changing it from nonlinear to linear. Finally we can use the same tweezer at a different atomic detuning to introduce an effective magnetic field acting as a spin filter. These results open the way to studying the coupling of particle, heat and spin transport in an atomic quantum point contact.