Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 36: Ultra-cold atoms, ions and BEC IV (with Q)

A 36.3: Talk

Thursday, March 20, 2014, 11:00–11:15, BEBEL E34

Field ionization of rubidium atoms near nanotips — •Markus Stecker, Peter Federsel, Hannah Schefzyk, Andreas Günther, and József Fortágh — Physikalisches Institut, Universität Tübingen, Germany

Detection of correlations in ultracold quantum gases requires a well suited local single atom detection scheme. For this purpose, we investigate the possibility of using charged nanotips. Due to the strong field enhancement at the tip apex, low voltages are sufficient to field ionize nearby rubidium atoms. As the ionization volume is on the length scale of the tip radius and the ions are detected with single particle resolution, this scheme should allow for local, in-situ investigation of ultracold atomic clouds.

We present the first steps towards this new detection scheme. Using a pulsed electrochemical etching technique, we produce sharp tungsten tips with variable length and nanometer sized tip radii. The field enhancement of the tip is characterized by electron field emission measurements. We demonstrate field ionization of rubidium at a single charged nanotip and investigate adsorption effects. As a next step, cold magneto-optically trapped atoms are ionized close to a tungsten nanotip.