Hannover 2013 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 2: Precision measurements and metrology I

Q 2.1: Group Report

Monday, March 18, 2013, 11:00–11:30, F 128

Quantum Metrology and Tomography with Bose–Einstein Condensates — •Roman Schmied, Caspar Ockeloen, Max Riedel, and Philipp Treutlein — Departement Physik, Universität Basel, Klingelbergstrasse 82, 4056 Basel, Schweiz

We present our recent results on the creation, manipulation, use, and analysis of entangled states of Bose–Einstein condensates of about 1000 Rubidium-87 atoms.

We have used a Bose–Einstein condensate as an interferometric scanning probe to map out a microwave field near a chip surface with a few micrometers resolution [1]. Using entanglement between the atoms we overcome the standard quantum limit of interferometry by 4 dB and maintain enhanced performance for interrogation times up to 20 ms. This demonstrates the usefulness of quantum metrology with entangled states when the particle number is limited due to the small probe size, and extends high-precision atomic magnetometry to the micrometer scale and microwave frequencies.

To analyze the many-body states of our Bose–Einstein condensates we extend our previously published quantum-state tomography [2] by enforcing that tomographically reconstructed many-body density matrices are positive semi-definite. We use this method to extract quantitative data such as the Fisher information.

[1] C.F. Ockeloen et al., submitted.

[2] R. Schmied and P. Treutlein, New J. Phys. 13, 065019 (2011).