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Q: Fachverband Quantenoptik und Photonik

Q 32: Poster: Quantum gases, ultracold atoms and molecules

Q 32.73: Poster

Mittwoch, 19. März 2014, 16:30–18:30, Spree-Palais

Accurate Mesoscopic Atom Counting in a Novel Hybrid Trap — •Ion Stroescu, David B. Hume, Wolfgang Muessel, Helmut Strobel, Daniel Linnemann, Jonas Schulz, and Markus K. Oberthaler — Kirchhoff-Institut für Physik, Universität Heidelberg, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany

Many cold atom experiments rely on precise atom number detection, especially in the context of quantum-enhanced metrology where effects at the single particle level are important. We present the limits of state-selective atom number counting via resonant fluorescence detection for mesoscopic samples of magneto-optically trapped atoms. We characterize the precision of these fluorescence measurements and by investigating the primary noise sources, we obtain single-atom resolution for atom numbers as high as 1200.

With the addition of a blue-detuned light sheet barrier, we create a novel hybrid trap for neutral atoms, which allows us to extend our atom counting capabilities to two internal atomic states, for which we reach single-atom resolution for up to 500 particles in each state. This capability is an essential prerequisite for future experiments with highly entangled states of mesoscopic atomic ensembles.

Furthermore, the hybrid trap enables experimental access to the rate of light-assisted collisions in a strongly damped, dissipative system. We observe effects that are not explained by thermal reaction rate theory.

Finally, we show multiple signatures of a stochastic resonance in our system, including an increased signal-to-noise ratio for added thermal noise and a measurement of the phase lag of the non-linear response.