Patent ID: 8536508

Claim:
A source for a heralded single photon, comprising: a correlated photon-pair generator that provides bursts of multiple photon pairs that may be odd or even in number of pairs, one of each pair having a first but not a second characteristic and the other of each pair having the second but not the first characteristic; a first optical path for photons of said pairs having the first characteristic; a second optical path for photons of said pairs having the second characteristic; a two-photon absorber in said first optical path that, for each burst of photons, reduces the number of first characteristic photons in said first path to zero or one, depending on whether the number of photon pairs in said burst is an even or odd number; and a photon detector in said second path having a heralding signal output depending on the even/odd characteristic of the number of photon pairs in said burst.