Mainz 2026 – scientific programme

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A: Fachverband Atomphysik

A 17: Ultra-cold Atoms, Ions and BEC II (joint session A/Q)

A 17.2: Talk

Wednesday, March 4, 2026, 15:00–15:15, N 1

Measuring inter-atomic friction with ultracold gases — •Silvia Hiebel, Sabrina Burgardt, Julian Feß, and Artur Widera — RPTU University Kaiserslautern-Landau

Usually, friction is characterized at the macroscopic scale. Over the past 25 years, microscopic measurements have become possible – for example, by dragging single atoms across surfaces with lateral force microscopes or by studying lubricity with dipole potentials acting on trapped ions. Yet, to understand transport in complex media, we also need direct access to friction at the level of individual atoms embedded in a gaseous environment.

We present our measurements of the friction of single atoms in a tilted optical lattice interacting with an ultracold atomic bath. A one-dimensional lattice allows controlled transport of individual atoms with tunable transport parameters, generating well-defined forces that can exceed gravity by several orders of magnitude and enabling access to distinct diffusion regimes. By pulling the single probe atoms through a dense ultracold bath, we observe the interplay between the driven impurity and its environment and extract the resulting effective friction.

Keywords: single atoms; friction; diffusion