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

We present a system of four ring resonators capable of generating programmable polarization and frequency-bin entangled photon pairs on an integrated photonic device. Each ring is pumped with a continuous wave, generating photon pairs with the same polarization in two pairs of frequency bins via spontaneous fourwave mixing. We show that the density operator of the generated state represents a hyperentangled state in the polarization and frequency bin degrees of freedom. We also calculate the generation rate of the state.