Generation of time-energy entangled photons on a silicon chip

An integrated source of time-energy entangled photons is demonstrated through resonantly enhanced spontaneous four-wave mixing in a silicon micro-ring resonator. A Franson type set-up is employed to show the quantum interference between photon pairs with a visibility exceeding 90% and a violation of the Bell's inequality by more than 10 standard deviations. The high spectral brightness and the extremely small footprint of our source make it suitable for the development of quantum information protocols integrated on chip