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arXiv · 1306.2677

Optimal quantum-enhanced interferometry using a laser power source

Matthias D. Lang·Carlton M. Caves
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Abstract

We consider an interferometer powered by laser light (a coherent state) into one input port and ask the following question: what is the best state to inject into the second input port, given a constraint on the mean number of photons this state can carry, in order to optimize the interferometer's phase sensitivity? This question is the practical question for high-sensitivity interferometry. We answer the question by considering the quantum Cram{\'e}r-Rao bound for such a setup. The answer is squeezed vacuum.

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Matthias D. Lang, Carlton M. Caves. 2013-06-11. Optimal quantum-enhanced interferometry using a laser power source. https://doi.org/10.1103/physrevlett.111.173601

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