Mesoscopic conduction in ultracold Fermi gases

Samuel Häusler

David Stadler, Jean-Philippe Brantut, Jakob Meineke +2 more

C. J. Bolech

Xiaoyu Dai, Boyang Liu

The particle and spin transports through a quantum point contact between two Fermi gases with Raman-induced spin-orbit coupling are investigated. We show that the particle and spin conductances both demonstrate the structure of plateaus due to the mesoscopic scale of the quantum point contact. Compared with that of normal Fermi gases, the height of the plateau of the particle conductance is enhanced by the spin-orbit-coupling effect for the whole parameter space. This implies that the 0.7 anomaly observed in mesoscopic experiments is unlikely to be induced purely by the spin-orbit coupling. Furthermore, the generation of spin current is investigated in this system. We find that the spin current can be induced by only the bias of the spin difference between the two reservoirs for the case of vanishing two-photon detuning. When the two-photon detuning is nonzero, the spin current can also be generated by the bias of the total particle number between the two reservoirs.

Jean-Philippe Brantut, Jakob Meineke, David Stadler +2 more

In a mesoscopic conductor, electric resistance is detected even if the device is defect-free. We engineered and studied a cold-atom analog of a mesoscopic conductor. It consists of a narrow channel connecting two macroscopic reservoirs of fermions that can be switched from ballistic to diffusive. We induced a current through the channel and found ohmic conduction, even when the channel is ballistic. We measured in situ the density variations resulting from the presence of a current and observed that density remains uniform and constant inside the ballistic channel. In contrast, for the diffusive case with disorder, we observed a density gradient extending through the channel. Our approach opens the way toward quantum simulation of mesoscopic devices with quantum gases.

Selim Jochim