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

Hwang Lee, Pieter Kok, Nicholas J. Cerf, and Jonathan P. Dowling

Physical Review A 65, 030101, Rapid Communication (2002)


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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© 2017 Pieter Kok

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