A folded-sandwich polarization-entangled two-color photon pair source with large tuning capability for applications in hybrid quantum architectures

TL;DR

This paper presents a versatile, high-fidelity two-color entangled photon pair source with large wavelength tuning capabilities, suitable for hybrid quantum systems and quantum communication applications.

Contribution

It introduces a novel folded-sandwich design using a Fresnel rhomb and compensation crystals for adaptable entangled photon generation.

Findings

Achieved entanglement fidelity of 0.753 at specific wavelengths.

Demonstrated adaptability to various wavelength combinations.

Discussed potential improvements for setup enhancement.

Abstract

We demonstrate a two-color entangled pho ton pair source which can be adapted easily to a wide range of wavelengths 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 $F = 0.753 \pm 0.021$ is demonstrated and improvements of the setup are discussed.