Entanglement swapping using low-noise nanowire detectors and off-the-shelf devices

Entanglement swapping, also considered as quantum teleportation of quantum entanglement, underpins the realization of quantum networks. For networks relying on two-photon interference, the performance of such swapping is characterized by the Hong-Ou-Mandel interference visibility. Using fiber-coupled and state of the art low-noise superconducting nanowire single photon detectors, we present measurements of such interference between telecommunication-band photons originating from independent off-the-shelf spontaneous down-conversion sources. The interference is characterized using two and three-fold coincidence detections, finding high visibility in both cases owing to our low-noise photon detectors. Further, the results are supported by a theoretical model based on Gaussian-state characterization functions. Our experiment, integrated within the Fermilab Quantum Network and useful DOE's Quantum Internet Blueprint testbeds suggests that quantum networks can be realized with practical devices.