A photonic chip coupled to a highly nonlinear crystal and a fiber array unit. The crystal produces entangled visible-telecom photon pairs, which are processed on silicon nitride and silicon photonic integrated circuits enabling a compact and versatile platform to link visibly accessed quantum nodes over existing telecommunications infrastructure. Credit: RIT
The Rochester Quantum Network transmits information by sending single photons through two fiber-optic telecommunications lines.
Researchers at the University of Rochester and Rochester Institute of Technology have recently linked their campuses using an experimental quantum communications network built with two optical fibers. In a new paper published in Optica Quantum, the team introduces the Rochester Quantum Network (RoQNET), which transmits information using single photons over approximately 11 miles of fiber-optic cable at room temperature and optical wavelengths.
Quantum communications networks could greatly enhance the security of transmitted information by making it impossible to copy or intercept messages without detection. These systems rely on quantum bits, or qubits, which can be made from atoms, superconductors, or even imperfections in materials like diamond. Among these, photons—individual light particles—are the most suitable qubit for long-distance quantum communication.
The advantages of photons over other qubits
Photons are especially attractive for quantum communication because they can, in theory, travel through the fiber-optic telecommunications lines that already span the globe. In the future, a variety of qubit types will likely be used, since sources like quantum dots or trapped ions offer specific benefits for applications in quantum computing and sensing. Even so, photons remain the most compatible with current communications infrastructure. The new paper focuses on enabling quantum communication between different types of qubits within a network.
“This is an exciting step creating quantum networks that would protect communications and empower new approaches to distributed computing and imaging,” says Nickolas Vamivakas, the Marie C. Wilson and Joseph C. Wilson Professor of Optical Physics, who led the University of Rochester’s efforts. “While other groups have developed experimental quantum networks, RoQNET is unique in its use of integrated quantum photonic chips for quantum light generation and solid-state based quantum memory nodes.”
Toward scalable and cost-effective quantum networking
The teams at the University of Rochester and RIT combined their expertise in optics, quantum information, and photonics to develop technology with photonic-integrated circuits that could facilitate the quantum network. Currently, efforts to leverage fiber-optic lines for quantum communication require bulky and expensive superconducting-nanowire-single-photon-detectors (SNSPDs), but they hope to eliminate this barrier.
“Photons move at the speed of light and their wide range of wavelengths enable communication with different types of qubits,” says Stefan Preble, professor in the Kate Gleason College of Engineering at RIT. “Our focus is on distributed quantum entanglement, and RoQNET is a test bed for doing that.”
Ultimately, the researchers want to connect RoQNET to other research facilities across New York State at Brookhaven National Lab, Stony Brook University, Air Force Research Laboratory, and New York University.
Reference: “Heralded telecom single photons from a visible-telecom pair source on a hybrid PPKTP-PIC platform” by Michael L. Fanto, Nick Vamivakas, Todd Hawthorne, Gregory A. Howland, Phil Battle, Venkatesh Deenadayalan, Vijay S. S. Sundaram, Mario Ciminelli, Evan Manfreda-Schulz, Thomas Palone, Gerald Leake, Daniel Coleman, Tony Roberts and Stefan F. Preble, 24 April 2025, Optica Quantum.
The research was supported by Air Force Research Laboratory.
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