Generation of nonclassical biphoton states through cascaded quantum walks on a nonlinear chip

We demonstrate a nonlinear optical chip that generates photons with reconfigurable nonclassical spatial correlations. We employ a quadratic nonlinear waveguide array, where photon pairs are generated through spontaneous parametric down-conversion and simultaneously spread through quantum walks between the waveguides. Because of the quantum interference of these cascaded quantum walks, the emerging photons can become entangled over multiple waveguide positions. We experimentally observe highly nonclassical photon-pair correlations, confirming the high fidelity of on-chip quantum interference. Furthermore, we demonstrate biphoton-state tunability by spatial shaping and frequency tuning of the classical pump beam

Flattened dispersion Ge 11.5 As 24 Se 64.5 glass waveguide for correlated photon generation: Design and analysis

A realizable waveguide structure providing ultra-low anomalous dispersion is achievable by changing the effective index of the top cladding using a SiO2 layer. Using atomic layer deposition to produce the silica layer, the dispersion can be tuned with a