Generation of polarization entangled photons using type-II doubly periodically poled lithium niobate waveguides

TL;DR

This paper demonstrates a method to generate polarization-entangled photon pairs at non-degenerate wavelengths using engineered type-II periodically poled lithium niobate waveguides, enabling advanced quantum communication applications.

Contribution

It introduces a novel quasi-phase-matching scheme that enables simultaneous phase-matching of two SPDC processes for direct entangled photon generation.

Findings

Successful generation of non-degenerate polarization-entangled photon pairs.

Potential for integration into quantum communication systems.

Enhanced control over entangled photon properties.

Abstract

In this paper, we address the issue of the generation of non-degenerate cross-polarization-entangled photon pairs using type-II periodically poled lithium niobate. We show that, by an appropriate engineering of the quasi-phase-matching grating, it is possible to simultaneously satisfy the conditions for two spontaneous parametric down-conversion processes, namely ordinary pump photon down-conversion to either extraordinary signal and ordinary idler paired photons, or to ordinary signal and extraordinary idler paired photons. In contrast to single type-II phase-matching, these two processes, when enabled together, can lead to the direct production of cross-polarization-entangled state for non degenerate signal and idler wavelengths. Such a scheme should be of great interest in applications requiring polarization-entangled non degenerate paired photons with, for instance, one of the entangled photons at an appropriate wavelength being used for local operation or for quantum storage in an atomic ensemble, and the other one at the typical wavelength of 1550 nm for propagation through an optical fiber.