Visible-wavelength polarization-entangled photon source for quantum communication and imaging

We present a polarization-entangled photon pair source operating in the visible light range around 532 nm. Employing collinear crossed-crystal scheme with type-I degenerate phase matching barium borate (BBO), our achieves brightness of 9.5 k pairs/s/mW and quantum state fidelity 98.3%, making it candidate for integration microscopes make use advantages mid-visible optimized single-photon detection technologies. In order to study potential applications, we trade-off between polarization entanglement visibility propose cases different filtering configurations source, capable up 1.23 M pairs/s/mW.