Interference from Two-Photon Sources in Silica-on-Silicon Circuits at Telecom Wavelength**Supported by the National Natural Science Foundation of China under Grant Nos 61627820, 61575191 and 61275045, and the National Basic Research Program of China under Grant Nos 2016YFA0301200, 2013CB632105.

Abstract

The integrated photonic chip is a promising way to realize future quantum technology. Here we demonstrate a two-photon interference in the standard telecommunication band on a silica-on-silicon integrated photonic chip. Two identical photons in the 1.55 μm band, which are indistinguishable in spatial, frequency and polarization, are generated by type-I collinear spontaneous parametric down-conversion via bismuth borate. The silica-on-silicon integrated chip, which has an insertion loss less than 1 dB, is a Mach–Zehnder interferometer with a thermo-optic phase shifter. A high visibility of 100% in the classical interference and 99.2% in the two-photon interference is achieved, indicating that the two-photon interference with high interference visibility on the chip is attained successfully.