Generation of hyperentangled photon pairs encoded in the time-bin and frequency-bin degree of freedom from silicon microrings

Multidimensional entangled photon states represent a useful resource for large-scale quantum communication networks. Among them, hyperentangled (HE) states, i.e. presenting simultaneous entanglement in several degrees of freedom (DoFs), stand out for their noise resilience. In this work, we demonstrate the generation of HE photon pairs in the time-bin and the frequency-bin DoFs through Spontaneous Four-Wave Mixing (SFWM) from two silicon-on-insulator high-brightness microring resonators.