A folded-sandwich polarization-entangled two-color photon pair source with large tuning capability for applications in hybrid quantum systems
Otto Dietz, Chris Müller, Thomas Kreißl, Ulrike Herzog, Tim Kroh, Andreas Ahlrichs, Oliver J. Benson · Applied Physics B · 2016
Abstract We demonstrate a two-color entangled photon pair source which can be adapted easily to a wide range of wavelength combinations. A Fresnel rhomb as a geometrical quarter-wave plate and a versatile combination of compensation crystals are key components of the source. Entanglement of two photons at the Cs D1 line (894.3 nm) and at the telecom O-band (1313.1 nm) with a fidelity of $$F=0.753 \pm 0.021$$ F = 0.753 ± 0.021 is demonstrated, and improvements of the setup are discussed.