A quantum-entangled photon traveled 35 kilometers under the streets of Boston

Illustration of Amazon’s logo on a black, orange, and tan background.
Illustration by Alex Castro / The Verge

Amazon and Harvard University have created a “quantum network” that transmitted an entangled photon from one quantum computer to another over 35 kilometers of fiber-optic cable.

Researchers from Harvard and Amazon’s AWS Center for Quantum Networking put a set of nodes around the Boston area to build a network capable of “efficiently catching, storing, and transferring information initially stored in light.” Like the internet we know, quantum networks send information carried by light — in this case, quantum-entangled photons. But they need “repeaters” to prevent those photons from scattering across long distances, as light is wont to do, and the repeaters have to be able to send the photon without breaking its entanglement and modifying…

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