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In-loop squeezing is real squeezing to an in-loop atom

H. M. Wiseman
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Abstract

Electro-optical feedback can produce an in-loop photocurrent with arbitrarily low noise. This is not regarded as evidence of `real' squeezing because squeezed light cannot be extracted from the loop using a linear beam splitter. Here I show that illuminating an atom (which is a nonlinear optical element) with `in-loop' squeezed light causes line-narrowing of one quadrature of the atom's fluorescence. This has long been regarded as an effect which can only be produced by squeezing. Experiments on atoms using in-loop squeezing should be much easier than those with conventional sources of squeezed light.

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H. M. Wiseman. 1998-05-26. In-loop squeezing is real squeezing to an in-loop atom. https://doi.org/10.1103/physrevlett.81.3840

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