Conduction of Ultracold Fermions Through a Mesoscopic Channel

TL;DR

This study demonstrates that ultracold fermions in a engineered mesoscopic channel exhibit ohmic conduction and contact resistance phenomena, providing a platform for quantum simulation of mesoscopic electronic devices.

Contribution

It introduces a cold-atom analog of a mesoscopic conductor, revealing contact resistance and conduction behavior in ballistic and diffusive regimes.

Findings

Ballistic channels show contact resistance at entrances and exits.

Diffusive channels display a spread of chemical potential drop.

Ohmic conduction occurs even in defect-free, ballistic channels.

Abstract

In a mesoscopic conductor electric resistance is detected even if the device is defect-free. We engineer and study 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 induce a current through the channel and find ohmic conduction, even for a ballistic channel. An analysis of in-situ density distributions shows that in the ballistic case the chemical potential drop occurs at the entrance and exit of the channel, revealing the presence of contact resistance. In contrast, a diffusive channel with disorder displays a chemical potential drop spread over the whole channel. Our approach opens the way towards quantum simulation of mesoscopic devices with quantum gases.