Compact Non‐Degenerate Entangled‐Photon Source and Near‐Infrared‐To‐Telecom Quantum Teleportation

The polarization‐entangled photon source (PEPS) at non‐degenerated wavelengths is pivotal to connect quantum systems working at different wavelengths, with the assistance of quantum teleportation. Here, a compact Sagnac‐type photon source is designed and demonstrated, in which two photons with wavelengths at 810 and 1550 nm are highly entangled in polarization degree of freedom. The two photons are generated from a periodically poled lithium niobate crystal pumped with a 532 nm continuous‐wave laser, via type‐0 nondegenerate spontaneous parametric down‐conversion. The polarization of three lights is rotated by a single periscope, which makes the Sagnac interferometer compact and stable. The generated two photons are with high brightness of pairs/s/mW, which are highly entangled with fidelity of . The entanglement is verified by violating the Clauser‐Horne‐Shimony‐Holt inequality with . Finally, teleportation is demonstrated with this nondegenerate source, in which photonic states at 810 nm is teleported to 1550 nm with fidelity of .