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arXiv · 0810.3545

Mesoscopic atomic entanglement for precision measurements beyond the standard quantum limit

J. Appel·P. J. Windpassinger·D. Oblak·U. B. Hoff·N. Kjaergaard·E. S. Polzik
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Abstract

Squeezing of quantum fluctuations by means of entanglement is a well recognized goal in the field of quantum information science and precision measurements. In particular, squeezing the fluctuations via entanglement between two-level atoms can improve the precision of sensing, clocks, metrology, and spectroscopy. Here, we demonstrate 3.4 dB of metrologically relevant squeezing and entanglement for ~ 10^5 cold cesium atoms via a quantum nondemolition (QND) measurement on the atom clock levels. We show that there is an optimal degree of decoherence induced by the quantum measurement which maximizes the generated entanglement. A two-color QND scheme used in this paper is shown to have a number of advantages for entanglement generation as compared to a single color QND measurement.

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J. Appel, P. J. Windpassinger, D. Oblak, U. B. Hoff, N. Kjaergaard, E. S. Polzik. 2009-05-28. Mesoscopic atomic entanglement for precision measurements beyond the standard quantum limit. https://doi.org/10.1073/pnas.0901550106

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