Patent ID: 8605288
Filing Date: 2013-12-10
Classification: G01C,H04B,H04L

Abstract:
1. An optical system configured to generate entangled photon states, the system comprising a non-classical single photon source configured to output identical photons separated by a time interval; and an interferometer comprising, a first path through said interferometer and second path through said interferometer, first directing elements configured to direct photons to follow the first path, second directing elements configured to direct photons to follow the second path, wherein in said second path the photons travel through said interferometer in a direction opposite to a direction through which the photons travel through said interferometer in said first path; and a phase shifter configured to vary the relative phase shift between photons following the first path and photons following the second path, the system being configured such that photons travelling through the first path have a different polarisation to those travelling through the second path, wherein a difference in path length between the first path and the second path is equal to the said time interval; and the system further comprising: a first detector for detecting photons which have followed said first path, a second detector for detecting photons which have followed said second path, and a processor configured to determine correlation between the results of said first and second detectors in order to select photons which have been entangled with the generated state.