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Quantum-Encrypted Information Transmitted Over Fiber More Than 600 Km Long

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Optical fibers.

The research team demonstrated that the new approach could accomplish repeater-like performance while tolerating optical losses beyond the traditional limit of 100 dB over a 605-kilometer-long quantum channel.

Credit: CC0 Public Domain

Researchers at the University of Leeds and Toshiba Europe in the U.K. established secure quantum communication over 605 kilometers (375 miles) of fiber through a new signal stabilization method.

The researchers used the twin-field quantum key distribution protocol, which enables two geographically separated users to establish a common secret bit-string by sharing photons, which are usually transmitted over an optical fiber.

The stabilization technique utilizes two optical reference signals at different wavelengths to minimize phase fluctuations over long distances.

The researchers demonstrated that this method could support repeater-like performance while accommodating losses outside the traditional limit of 100 decibels over a 605-kilometer-long quantum channel.

Toshiba Europe's Andrew Shields said, "This will allow us to build national- and continental-scale fiber networks connecting major metropolitan areas."

From Optica
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