Fig. 5: Visibility of two photon interference in the energy-time DoF for different input powers.

We performed a Franson experiment for each correlated resonance pair, labelled as \({\left\vert 0\right\rangle }_{s}{\left\vert 0\right\rangle }_{i}\) and \({\left\vert 1\right\rangle }_{s}{\left\vert 1\right\rangle }_{i}\), from which the frequency bin qubits are constructed (Fig. 2a). The points are obtained from the central peak of the coincidence histogram (see Fig. 4b). The solid green line represents the upper limit of the visibility achievable given the measured CAR as described by Eq. (4). The green dashed line marks the power for which the device generates 1 Gpair/s on-chip, while the red dashed line marks the power that correspond to a net rate of 1 Gpair/s after fiber coupling.