Researchers develop quantum communications network
Researchers at the University of Rochester and Rochester Institute of Technology recently connected their campuses with an experimental quantum communications network using two optical fibres.
In a paper, the scientists describe the experimental quantum communications network, designated Rochester Quantum Network or RoQNET, which uses single photons to transmit information around 11 miles along fibre-optic lines at room temperature using optical wavelengths.
Quantum communications networks have the potential to significantly enhance the security of information transmission, rendering messages impossible to clone or intercept without detection. Although qubits used in quantum communication can be physically created with atoms, superconductors, and even defects in materials like diamond, individual particles of light are the best type of qubit for long-distance quantum communications.
Many qubits will likely be utilised in the future because qubit sources, like quantum dots or trapped ions, each have advantages for specific applications in quantum computing or different types of quantum sensing. However, photons are the most appealing because they could theoretically be transmitted over fibre-optic telecommunications lines.
“This is a step to 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.”
The University of Rochester and RIT teams combined their expertise in optics, quantum information, and photonics to develop technology with photonic-integrated circuits that could facilitate a quantum network. Currently, efforts to leverage fibre-optic lines for quantum communication require bulky and expensive superconducting-nanowire single-photon detectors (SNSPDs), but the researchers 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 the RoQNET quantum communications network to other research facilities across New York State at Brookhaven National Lab, Stony Brook University, Air Force Research Laboratory, and New York University.
Image: A photonic chip coupled to a highly nonlinear crystal and a fibre 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.
Paper: https://doi.org/10.1364/OPTICAQ.546774
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