Heralding multiple photonic pulsed Bell-pairs via frequency-resolved entanglement swapping

TL;DR

This paper demonstrates a quantum experiment where entanglement swapping from two independent sources creates multiple heralded Bell states, advancing quantum network capabilities by distinguishing several Bell pairs simultaneously.

Contribution

It introduces a method to generate and verify multiple heralded Bell pairs via frequency-resolved entanglement swapping from multimode sources.

Findings

Successfully distinguished up to five orthogonal Bell pairs

Verified entanglement through joint spectra and quantum interference

Limited only by the entanglement of the sources

Abstract

Entanglement is a unique property of quantum systems and an essential resource for many quantum technologies. The ability to transfer or swap entanglement between systems is an important protocol in quantum information science. Entanglement between photons forms the basis of distributed quantum networks and the demonstration of photonic entanglement swapping is essential for their realization. Here an experiment demonstrating entanglement swapping from two independent multimode time-frequency entangled sources is presented, resulting in multiple heralded temporal-mode Bell states. Entanglement in the heralded states is verified by measuring conditional anti-correlated joint spectra as well as quantum beating in two-photon interference. Our proof-of-concept experiment is able to distinguish up to five orthogonal Bell pairs within the same setup, limited in principle only by the entanglement of the sources.