Abstract
We report on the experimental investigation of individual Cs atoms impinging on a dilute cloud of ultracold Rb atoms with variable density. We study the relaxation of the initial nonthermal state and detect the effect of single collisions which has so far eluded observation. We show that, after few collisions, the measured spatial distribution of the tracer atoms is correctly described by a Langevin equation with a velocity-dependent friction coefficient, over a large range of Knudsen numbers. Our results extend the simple and effective Langevin treatment to the realm of light particles in dilute gases. The experimental technique developed opens up the microscopic exploration of a novel regime of diffusion at the level of individual collisions.
- Received 23 February 2017
DOI:https://doi.org/10.1103/PhysRevLett.118.263401
© 2017 American Physical Society
Physics Subject Headings (PhySH)
Focus
Observing Diffusion Atom by Atom
Published 30 June 2017
The tracking of individual atoms diffusing in a cold, rarefied gas reveals the influence that a single impact has on randomizing the motion.
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