Qunnect and Cisco Demonstrate Quantum Entanglement over a Quantum Network in New York City - Quantum Computing Report
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Qunnect and Cisco Demonstrate Quantum Entanglement over a Quantum Network in New York City In a continued advance in quantum networking Qunnect has teamed up with Cisco to demonstrate high-speed, high-fidelity entanglement swapping on their GothamQ network in New York City. The portion of the GothamQ network, pictured above, is arranged is a hub-and-spoke topology. S1 and S2 shown in the picture are independent entanglement sources located in Brooklyn while the hub H, located at QTD Systems‘ data center at 60 Hudson Street in Manhattan, is where the entanglement swapping happens. The nodes are connected by 17.6 km of standard telecom grade fiber cable that run under the city streets with all the potential noise sources that might occur and the hardware used is Qunnect’s Carina product which includes quantum networking components, detectors, time taggers, and synchronization electronics. The Carina hardware runs at room-temperature at the outlying S1 and S2 nodes using SPAD (Single Photon Avalanche Diode) detectors while the hardware at the hub requires cryogenic cooling because it uses SNSPDs (Superconducting Nanowire Single Photon Detector). The system is all managed by Cisco’ quantum networking orchestration software which provides for correlations, coordination, calibration, and data management. This system achieves the highest entanglement swapping rates reported to date of 1.7M+ pairs/hour locally and 5,400 pairs/hour over deployed fiber. The polarization fidelity achieved was above 99%. This technology will become very important as organizations establish quantum data centers that will connect multiple quantum computers together for large quantum processing tasks. In addition, quantum entanglement is one of the necessary technologies for creating long range quantum networks that will utilize quantum repeaters to maintain the signal over a long distance. The other key technology needed to create a quantum repeater is a quantum memory and those are still in development.
The Quantum Computing Report by GQI has previously published related articles about the quantum networking activities of these two companies. An article about Qunnect’s GothamQ network is available here and another one describing the deployment of Qunnect’s Carina product at Montana State University is available here. And recently Cisco announced a collaboration with IBM regarding data center quantum networks that we reported on here. For more about this demonstration, view a press releases posted on the Qunnect website here and blogs posted on the Cisco and Qunnect websites here and here. A technical pre-print paper has been posted on arXiv here and the Qunnect and Cisco teams will hold a webinar deep dive into the technology on February 26, 2026 that you can register to attend here.