Stuttgart 2012 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 55: SYQM: Quantum limited measurement applications 1

Q 55.5: Talk

Friday, March 16, 2012, 12:00–12:15, V47.01

Entanglement-Enhanced Interferometer on an Atom Chip — •Caspar Ockeloen, Roman Schmied, Max F. Riedel, and Philipp Treutlein — Departement Physik, Universität Basel, Switzerland

We experimentally realize a Ramsey interferometer operating beyond the standard quantum limit (SQL), using two internal spin states of a two-component Bose-Einstein condensate. We first produce spin-squeezed states by controlled collisional interactions between the atoms using a state-dependent microwave near-field potential. We observe spin noise reduction by up to 4.5 dB below the SQL with a spin coherence of >98%, corresponding to a depth of entanglement of at least 40 particles.

Using such spin-squeezed states as interferometer input states, we demonstrate performance beyond the SQL. Our interferometer outperforms an ideal classical interferometer with the same number of particles (≈1300) for interrogation times up to 5 ms.

These experiments are performed on a micro-fabricated atom chip providing small and well-localized trapped atomic ensembles. This makes our technique promising for high-precision measurements with micrometer spatial resolution, e.g. probing near-field magnetic or microwave fields close to the chip surface.