Faithful entanglement swapping based on sum-frequency generation

TL;DR

This paper demonstrates that sum-frequency generation can enable faithful entanglement swapping without post-selection, offering a practical alternative to linear optics protocols for quantum communication and cryptography.

Contribution

It introduces a method to achieve faithful entanglement swapping using sum-frequency generation, eliminating the need for post-selection in spontaneous parametric down-conversion.

Findings

Sum-frequency generation enables faithful entanglement swapping.

Experimental proof-of-principle validates the approach.

Potential for improved quantum communication protocols.

Abstract

We show that the entanglement resulting from an entanglement swapping operation performed with spontaneous parametric down-conversion can be made faithful without post-selection using sum-frequency generation. This invites us to revisit the sum-frequency process and from a proof-of-principle experiment, we demonstrate that it provides a realistic solution for non-linear optics at the single-photon level. This opens the way to attractive alternatives to six-photon protocols based on linear optics used e.g. for the heralded creation of maximally entangled pairs or for the implementation of device-independent quantum key distribution.