**Time/Venue** Tuesday, December 6 at 2:00 pm Pacific Time in Physics South 402 and via Zoom:

https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09

Meeting ID: 995 2349 9113 Passcode: 600704**Host** Ehud Altman**Title **Spread and erase — How electron hydrodynamics can eliminate the

Landauer-Sharvin resistance**Abstract** What is the ultimate limit of conductance of a metallic device of

lateral size W? In the ballistic limit, the answer is the

Landauer-Sharvin conductance, which is associated with an abrupt

reduction of the number of conducting channels when going from the

contacts to the device. However, the ballistic limit is not always the

best-case scenario, since adding strong electron-electron scattering can

take electrons to a viscous regime of transport for which

“super-ballistic” flows were recently studied. In this talk, we will

show that by a proper choice of geometry which resembles a “wormhole”,

it is possible to spread the Landauer-Sharvin resistance throughout the

bulk of the system, allowing its complete elimination by electron

hydrodynamics. This effect arises due to the interplay between geometry

and strong electron-electron scattering, which allows for a net transfer

of carriers from reflected to transmitted channels. Finally, we will

discuss a recent experiment in a Corbino geometry which realizes one

half of this “wormhole” geometry

Refs:

Theory: Phys. Rev. Lett. 129, 157701 (2022)

Experiment: Nature 609, 276–281 (2022)