Nanofriction in Cold Ion Traps

TL;DR

This paper explores how cold ion traps can serve as a platform to study fundamental nanofriction phenomena, revealing static and dynamic friction behaviors through simulations of ion chains in periodic potentials.

Contribution

It demonstrates, via simulations, that cold ion chains exhibit frictional transitions analogous to classical models, providing a new experimental avenue for nanofriction research.

Findings

Static friction vanishes at a structural transition in ion chains.

Ion chains are always pinned but show Aubry-like transitions.

Dynamic friction can be measured through ringdown oscillations.

Abstract

Sliding friction between crystal lattices and the physics of cold ion traps are so far non-overlapping fields. Two sliding lattices may either stick and show static friction or slip with dynamic friction; cold ions are known to form static chains, helices, or clusters, depending on trapping conditions. Here we show, based on simulations, that much could be learnt about friction by sliding, via e.g. an electric field, the trapped ion chains over a periodic corrugated potential. Unlike infinite chains where, according to theory, the classic Aubry transition to free sliding may take place, trapped chains are always pinned. Nonetheless we find that a properly defined static friction still vanishes Aubry-like at a symmetric-asymmetric structural transition, ubiquitous for decreasing corrugation in both straight and zig-zag trapped chains. Dynamic friction can also be addressed by ringdown oscillations of the ion trap. Long theorized static and dynamic one dimensional friction phenomena could thus become exquisitely accessible in future cold ion tribology.