High-quality photonic entanglement for wavelength-multiplexed quantum   communication based on a silicon chip
  We report an efficient energy-time entangled photon-pair source based on four-wave mixing in a CMOS-compatible silicon photonics ring resonator. Thanks to suitable optimization, the source shows a large spectral brightness of 400\,pairs of entangled photons /s/MHz for $\rm 500\,\mu W$ pump power. Additionally, the resonator has been engineered so as to generate a frequency comb structure compatible with standard telecom dense wavelength division multiplexers. We demonstrate high-purity energy-time entanglement, i.e., free of photonic noise, with near perfect raw visibilities ($>$~98\%) between various channel pairs in the telecom C-band. Such a compact source stands as a path towards more complex quantum photonic circuits dedicated to quantum communication systems. 
Florent Mazeas, Michele Traetta, Marco Bentivegna, Florian Kaiser,   Djeylan Aktas, Weiwei Zhang, Carlos Alonso Ramos, Lutfi...
quant-ph physics.optics