Illinois Express Quantum Network for Distributing and Controlling Entanglement on Metro-Scale*

The Illinois Express Quantum Network (IEQNET) is a program for developing metro-scale quantum networking over deployed optical fiber infrastructure. While new technologies, such as quantum repeaters, will be needed to realize the long-term goals of quantum networking, IEQNET focuses on leveraging currently available technology (with provision for future upgrades as technology develops). Two of the prime needs in quantum information systems are distributing entanglement and using entanglement to perform quantum state teleportation. These needs should be met while simultaneously allowing higher-power classical signals to share the same fiber, both for the purposes of enabling communications to support quantum applications and for independent coexistence of high data-rate classical channels. We will summarize the main elements of the IEQNET architecture, that leverages software-defined-networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-nodes, as well as the status of its implementation at the three sites of the project in the Chicago metropolitan area. We will also show coexistence of quantum entangled and classical light over deployed optical fiber at the sites. Wavelength engineering/filtering allows milliwatts copropagating power with quantum light from a photon-pair source with broad entangled spectrum.