Patent ID: 8068740

Claim:
A secure optical communication system, comprising: a photon-pair generation circuit configured to generate pairs of photons with each photon pair including a first-channel photon and a second-channel photon; a transmitting circuit configured to receive first-channel photons, and modulate the first-channel photons according to a stream of data using a first optical circulator to produce first-modulated photons, wherein the first optical circulator includes a first beam splitter having a first reflection coefficient R 1 plus a plurality of mirrors to form a first internal path having a length of distance D 1 , and wherein the first optical circulator further includes a circulator half-wave plate inserted within the first internal path, the circulator half-wave plate allowing photons having a first polarity to pass through with 0 degree phase shift while photons having a second polarity to pass through with 180 degree phase shift; and a receiving circuit configured to receive second-channel photons, pass the second-channel photons through a complementary optical circulator to produce second second-processed photons, and detect relative timing between the first-modulated photons and the second-processed photons to recover the stream of data.