Heidelberg 2015 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 14: Precision Measurements and Metrology II (with A)

Q 14.1: Group Report

Monday, March 23, 2015, 14:30–15:00, P/H1

Quantum atom optics: states, schemes and applications — •Helmut Strobel, Daniel Linnemann, Arno Trautmann, Tobias Rentrop, Wolfgang Muessel, Philipp Kunkel, Sören Bieling, Fabian Olivares, Marcell Gall, and Markus K. Oberthaler — Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, Heidelberg

We report on the generation of non-Gaussian (NG) spin states via unstable fixed point dynamics in mesoscopic ⁸⁷Rb spinor Bose-Einstein condensates. We present a general method to extract the Fisher information, which reveals entanglement in a regime where no spin squeezing is present. The applicability of the detected quantum resource is explicitly confirmed by the implementation of a Bayesian phase estimation protocol [1].

A different class of NG spin states is generated via spin changing collisions involving three Zeeman sublevels, analogous to parametric down-conversion in quantum optics. Since this process is coherent, it can be utilized as active beam splitters in an interferometer. We characterize the phase-dependent output signal and find a phase sensitivity beyond the classical limit for average atom numbers as small as ∼ 1 per side mode inside the interferometer.

We also present recent results in motional interferometry of Lithium impurities immersed in a background of Bose-condensed Sodium for the extraction of small changes of their effective mass. We confirm predicted Feshbach resonances for the interaction of ²³Na with ⁷Li which is a prerequisite for systematic studies of the impurity mass.

[1] H. Strobel et al. Science 345 424-427 (2014)