Velocity tuning of friction with two trapped atoms

• Published in: Nature physics Vol. 11; no. 11; pp. 915 - 919
• Main Authors: Gangloff, Dorian, Bylinskii, Alexei, Counts, Ian, Jhe, Wonho, Vuletić, Vladan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2015; Nature Publishing Group
• Subjects: 639/301/119/544; 639/766/36; Atomic; Atomic physics; Atomic structure; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Control systems; Dissipation; Dynamic range; Dynamical systems; Friction; letter; Lubricity; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Physics; Theoretical; Tuning
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys3459

To study atomic-scale friction in a controlled environment, researchers used two trapped, laser-cooled ions in an additional optical potential. This set-up provides a better understanding of the interplay between thermal and structural lubricity. Our ability to control friction remains modest, as our understanding of the underlying microscopic processes is incomplete 1 , 2 , 3 . Atomic force experiments 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 have provided a wealth of results on the dependence of nanofriction on structure 5 , 6 , velocity 7 , 8 , 9 , 10 and temperature 11 , 12 , 13 , but limitations in the dynamic range, time resolution, and control at the single-atom level have hampered a description from first principles 3 . Here, using an ion-crystal system with single-atom, single-substrate-site spatial and single-slip temporal resolution 15 , 16 , we measure the friction force over nearly five orders of magnitude in velocity, and contiguously observe four distinct regimes, while controlling temperature and dissipation. We elucidate the interplay between thermal and structural lubricity for two coupled atoms, and provide a simple explanation in terms of the Peierls–Nabarro potential 17 . This extensive control at the atomic scale enables fundamental studies of the interaction of many-atom surfaces, possibly into the quantum regime.