Massive Entangled State Engineering and Control of Cold Atoms

Niels Bohr Institute, Copenhagen University

Friday, 30 November 2007, 3.30pm, EN101, Ground Floor, Engineering Building, Hawthorn.

Deterministic entanglement of atoms can be generated via an off-resonant interaction of light with a multi-atom ensemble combined with a quantum measurement and feedback. This approach has led to a number of results with room temperature atoms including the light-to-atoms quantum teleportation. In the talk I will concentrate on the recent applications of the quantum measurement as the state preparation tool for cold atoms. We have applied the quantum non-demolition interaction to a dipole trapped ensemble of Cs atoms and have demonstrated that spin squeezing of 10⁵ atoms can be achieved in this way. This result is directly relevant for the improvement of the microwave and optical clock accuracy beyond the standard quantum limit. Properly engineered light-atoms interaction can also serve as a quantum meter for the many-body entanglement already present in the atomic system. A recently developed method allows to detect atomic entanglement generated via magnetic ordering in strongly correlated systems of ultracold atoms. The atomic state is detected in the least invasive way, via a quantum non-demolition measurement on the transmitted light.

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