Signal NIST, UMD, and Qunnect Demonstrate Quantum Entanglement Over 62km of Aerial Commercial Fiber

Summary

Researchers from NIST, the University of Maryland's Joint Quantum Institute and quantum-networking company Qunnect announced a successful demonstration of entangled-photon distribution over 62 kilometers of real-world aerial commercial telecommunications fiber connecting NIST's Gaithersburg campus to the University of Maryland in College Park. Unlike buried fiber, aerial cable suspended from utility poles suffers severe polarization drift from wind, traffic vibration and temperature swings, which NIST physicist Oliver Slattery called about as bad a connection as you can possibly have. The team used Qunnect's automated polarization-compensation device to correct distortions in real time, achieving a distribution rate of 1,500 entangled photon pairs per second with a 92.8 percent success rate. They recorded a CHSH Bell-inequality violation sustained for over 20 consecutive hours, confirming high-fidelity entanglement preservation under adverse real-world conditions. The result suggests metropolitan-scale quantum networks can be deployed on existing commercial infrastructure rather than requiring dedicated underground installations.