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arXiv · 1801.06839

Direct observation of atom-ion non-equilibrium sympathetic cooling

Ziv Meir·Meirav Pinkas·Tomas Sikorsky·Ruti Ben-shlomi·Nitzan Akerman·Roee Ozeri
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Abstract

Sympathetic cooling is the process of energy exchange between a system and a colder bath. We investigate this fundamental process in an atom-ion experiment where the system is composed of a single ion, trapped in a radio-frequency Paul trap, and prepared in a coherent state of ~200 K and the bath is an ultracold cloud of atoms at μK temperature. We directly observe the sympathetic cooling dynamics with single-shot energy measurements during one, to several, collisions in two distinct regimes. In one, collisions predominantly cool the system with very efficient momentum transfer leading to cooling in only a few collisions. In the other, collisions can both cool and heat the system due to the non-equilibrium dynamics of the atom-ion collisions in the presence of the ion-trap's oscillating electric fields. While the bulk of our observations agree well with a molecular dynamics simulation of hard-sphere (Langevin) collisions, a measurement of the scattering angle distribution reveals forward-scattering (glancing) collisions which are beyond the Langevin model. This work paves the way for further non-equilibrium and collision dynamics studies using the well-controlled atom-ion system.

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Ziv Meir, Meirav Pinkas, Tomas Sikorsky, Ruti Ben-shlomi, Nitzan Akerman, Roee Ozeri. 2018-01-21. Direct observation of atom-ion non-equilibrium sympathetic cooling. https://doi.org/10.1103/physrevlett.121.053402

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