Programmable integrated source of polarization and frequency-bin hyperentangled photon pairs

We present a system capable of generating programmable polarization and frequency-bin hyperentangled photon pairs in an integrated photonic device. The structure is composed of ring resonators, each generating photon pairs with the same polarization in two pairs of frequency bins via spontaneous four-wave mixing. By combining several rings and controlling the amplitude and phase of the pump field, one can construct several hyperentangled states in a piece-by-piece fashion. For example, we consider a system composed of four rings and show that the density operator of the generated state describes a polarization and frequency-bin hyperentangled state. Finally, we calculate the expected generation rate and discuss the device efficiency.