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Linear optics and projective measurements alone suffice to create large-photon-number path entanglement

Hwang Lee·Pieter Kok·Nicolas J. Cerf·Jonathan P. Dowling
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Abstract

We propose a method for preparing maximal path entanglement with a definite photon number N, larger than two, using projective measurements. In contrast with the previously known schemes, our method uses only linear optics. Specifically, we exhibit a way of generating four-photon, path-entangled states of the form |4,0> + |0,4>, using only four beam splitters and two detectors. These states are of major interest as a resource for quantum interferometric sensors as well as for optical quantum lithography and quantum holography.

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Hwang Lee, Pieter Kok, Nicolas J. Cerf, Jonathan P. Dowling. 2001-09-18. Linear optics and projective measurements alone suffice to create large-photon-number path entanglement. https://doi.org/10.1103/physreva.65.030101

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