Observation of individual tracer atoms in an ultracold dilute gas
Abstract
Understanding the motion of a tracer particle in a rarefied gas is of fundamental and practical importance. We report the experimental investigation of individual Cs atoms impinging on a dilute cloud of ultracold Rb atoms with variable density. We study the nonequilibrium relaxation of the initial nonthermal state and detect the effect of single collisions which has eluded observation so far. We show that after few collisions, the measured spatial distribution of the light tracer atoms is correctly described by a generalized Langevin equation with a velocitydependent friction coefficient, over a large range of Knudsen numbers.
 Publication:

arXiv eprints
 Pub Date:
 November 2016
 arXiv:
 arXiv:1611.01452
 Bibcode:
 2016arXiv161101452H
 Keywords:

 Physics  Atomic Physics;
 Condensed Matter  Statistical Mechanics;
 Physics  Fluid Dynamics
 EPrint:
 Phys. Rev. Lett. 118, 263401 (2017)