| 摘要 |
Method for selective generation of individual photons or photon pairs in an optical channel (16, 17) with the following steps: - generation of a two-photons (photon pair); - spatial separation of the photon pair whilst retaining the quantum mechanical correlation in the event that the photons are emitted linearly; - injection of each photon into an optical channel (14, 14', 14"), one channel (15, 15', 15") incorporating an interferometer (7-13) with a variable optical path lengths difference .delta.1F-.delta.1S and the other channel incorporating an optical delay section (19) of optical lengths .delta.1; - spatial merging of both channels by means of a beam splitter (18, 31-36); - co-ordination of the values .delta.1F, .delta.1S, and .delta.1 such that t he probability K for coincidences between the outputs (16, 17) of the beam splitter amounts selectively to K=0 or K=1 or to a predetermined intermediate value, K=0 corresponding to a photon pair in one of the outputs channels (16, 17) of the beam splitter, and K=1 corresponding to two individual photons in both outputs channels of the beam splitter. Using the present invention, it is possible to realize an optical switch or gate for one or two photon states, as desired, which can be used in quantum cryptography and as a basic element fora quantum-optical computer.
|
