Experimental demonstration of a quantum router

TL;DR

This paper demonstrates a quantum router using linear optics that coherently routes single-photon signals based on a control photon, preserving quantum states and generating entanglement, crucial for quantum networks.

Contribution

It presents the first experimental realization of a genuine quantum router with linear optics, enabling coherent routing and entanglement generation for quantum communication.

Findings

Successfully demonstrated quantum routing of single photons.

Preserved the qubit state of the signal photon during routing.

Generated entanglement between control and signal photons.

Abstract

The router is a key element for a network. We describe a scheme to realize genuine quantum routing of single-photon pulses based on cascading of conditional quantum gates in a Mach-Zehnder interferometer and report a proof-of-principle experiment for its demonstration using linear optics quantum gates. The polarization of the control photon routes in a coherent way the path of the signal photon while preserving the qubit state of the signal photon represented by its polarization. We demonstrate quantum nature of this router by showing entanglement generated between the initially unentangled control and signal photons, and confirm that the qubit state of the signal photon is well preserved by the router through quantum process tomography.