USTC Entangles Quantum Memories Over 260 Miles, Beating PLOB Bound Beyond 132 Miles
Updated
Updated · SDxCentral · Aug 18
USTC Entangles Quantum Memories Over 260 Miles, Beating PLOB Bound Beyond 132 Miles
1 articles · Updated · SDxCentral · Aug 18
Summary
420 kilometers of optical fiber linked two rubidium-atom quantum memories, and the team verified entanglement with concurrence of 0.046 ± 0.022.
The result matters because the memory-based scheme scaled with the square root of channel transmittance, outperforming direct photon transmission at losses equivalent to more than about 132 miles of fiber.
Using the DLCZ protocol, photons from both memories interfered at a middle node; the team also converted them to the 1,522-nm telecom S-band and stabilized phase across the long optical path.
The setup tested an intercity-scale path rather than nodes physically 260 miles apart, though researchers said the phase-locking method could be adapted to comparable geographic separations.
The work extends USTC's 2024 three-node network from 7.7 miles toward quantum repeaters and wider quantum communication, computing and sensing networks.