Patent ID: 7317574

Claim:
A method of creating entanglement between first and second atomic ensembles, comprising: propagating a first pulse of light generated in said pulsed source of light into the first atomic ensemble having a first collective excitation state, wherein photons in said first pulse of light have an energy that can excite the first atomic ensemble to the said first collective excitation state so as to generate first photons; propagating a second pulse of light generated in said pulsed source of light into the second atomic ensemble having a second collective excitation state, wherein photons in said second pulse of light have an energy that can excite the second atomic ensemble to the second collective excitation state so as to generate second photons; interfering the first and second photons at an interferer while preventing photons not resulting from the generation of collective excitations in said first atomic ensemble and said second atomic ensemble from reaching said interferer by arranging a first filter in a first optical path between said first atomic ensemble and said interferer, and a second filter in a second optical path between said second atomic ensemble and said interferer; detecting the interfered photons so as to establish entanglement between the first and second atomic ensembles and; detecting the interfered photons with a first or second photon detector and controlling said first single photon detector and said second single photon detector with a photo detector controller.