Discrete and Parallel Frequency-Bin Entanglement Generation from Quantum Frequency Comb

Photons’ frequency degree of freedom is promising to realize large-scale quantum information processing. Quantum frequency combs (QFCs) generated in integrated nonlinear microresonators can produce multiple frequency modes with narrow linewidth. Here, polarization-entangled QFCs are utilized to generate discrete frequency-bin entangled states. Fourteen pairs of polarization-entangled photons with different frequencies are simultaneously transformed into frequency-bin entangled states. The characteristic of frequency-bin entanglement is demonstrated by Hong-Ou-Mandel interference, which can be performed with single or multiple frequency pairs in parallel. This work paves the way for harnessing large-scale frequency-bin entanglement and converting between different degrees of freedom in quantum information processing.