  The fruitful association of quantum and integrated photonics holds the
promise to produce, manipulate, and detect quantum states of light using
compact and scalable systems. Integrating all the building-blocks necessary to
produce high-quality photonic entanglement in the telecom wavelength range out
of a single chip remains a major challenge, mainly due to the limited
performance of on-chip light rejection filters. We report a stand-alone,
telecom-compliant, device that integrates, on a single substrate, a nonlinear
photon-pair generator and a passive pump rejection filter. Using standard
channel-grid fiber demultiplexers, we demonstrate the first entanglement
quantification of such a integrated circuit, showing the highest raw quantum
interference visibility for energy-time entangled photons over two
telecom-wavelength bands. Genuinely pure maximally entangled states can
therefore be generated thanks to the high-level of noise suppression obtained
with the pump filter. These results will certainly further promote the
development of more advanced and scalable photonic-integrated quantum systems
compliant with telecommunication standards.
