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arXiv · 1303.5888

Dissipative versus Conditional Generation of Gaussian Entanglement and Spin Squeezing

Denis V. Vasilyev·Christine A. Muschik·Klemens Hammerer
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Abstract

Spin squeezing of collective atomic spins can be achieved conditionally via probing with light and subsequent homodyne detection, as is done in a Quantum Nondemolition measurement. Recently it has been shown that squeezing can also be created unconditionally by a properly designed dissipative dynamics. We compare the two approaches in a Gaussian description, and optimize over all Gaussian light-matter interactions. We find that in the optimal unconditional scheme based on dissipation the level of squeezing scales as $d^{-1/2}$. In contrast, the optimal conditional scheme based on measurement of light -- which in fact is not a Quantum Nondemolition measurement -- can provide squeezing which scales as $d^{-1}$ in the most relevant regime of moderate optical depths. Our results apply directly also to the creation of entanglement in the form of non-local spin squeezing of two atomic ensembles.

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Denis V. Vasilyev, Christine A. Muschik, Klemens Hammerer. 2013-05-28. Dissipative versus Conditional Generation of Gaussian Entanglement and Spin Squeezing. https://doi.org/10.1103/physreva.87.053820

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