Fig. 1: Integrated device scheme and linear characterization.

a Scheme of the integrated device. The input and output channels waveguide are inverse tapered. The rainbow block represent the demultiplexer. b-i,ii Transmission spectra from the output signal and idler channels in the spectral region of one of the pairs employed in the frequency-bin entanglement experiment. The dashed and the solid line are a Lorentzian fit for the resonance pair labelled as \({\left\vert 1\right\rangle }_{s}{\left\vert 1\right\rangle }_{i}\) and \({\left\vert 0\right\rangle }_{s}{\left\vert 0\right\rangle }_{i}\), respectively. c Transmission spectrum of the DEMUX’s channels-only, i.e. input and output coupler contribution have been removed. The dotted vertical lines represent one example of employed resonances (blue for signal and red for idler) and the pump wavelength (green).