Patent ID: 7302187

Claim:
An apparatus comprising: a source of photons; a parametric down-converter wherein at least some of said photons are each converted into a pair of first and second down-converted photons wherein each said down-converted photon is in a quantum-entangled state, and wherein alteration of a characteristic of one of said first and second down-converted pair of photons alters a corresponding characteristic in the other of said first and second down-converted pair of photons; a receiver having a first channel to receive said first down-converted photons from said parametric down-converter and a first polarization detection arrangement operably coupled to said first channel to detect polarization of said first down-converted photons, and a second channel to receive said second down-converted photons from said parametric down-converter and a second polarization detection arrangement operably coupled to said second channel to detect polarization of said second down-converted photons; and a transmitter operably coupled to said first channel, said transmitter including a collapse event causation device for selectably causing a polarization alteration in said quantum entangled state of each photon in said pairs of said first and second down-converted photons.