Engineers Achieve Quantum Teleportation Over Active Internet Cables

Researchers at Northwestern University have successfully achieved quantum teleportation over a standard fiber optic cable carrying regular internet traffic, demonstrating that quantum and classical communication can coexist on existing infrastructure. The research has been published in the journal Optica. TechSpot reports: Nobody thought it would be possible to achieve this, according to Professor Prem Kumar, who led the study. "Our work shows a path towards next-generation quantum and classical networks sharing a unified fiber optic infrastructure. Basically, it opens the door to pushing quantum communications to the next level." "By performing a destructive measurement on two photons -- one carrying a quantum state and one entangled with another photon -- the quantum state is transferred onto the remaining photon, which can be very far away," said Jordan Thomas, a Ph.D. candidate in Kumar's laboratory and the paper's first author. "The photon itself does not have to be sent over long distances, but its state still ends up encoded onto the distant photon."

Prior to this study, many researchers were skeptical about the feasibility of quantum teleportation in cables carrying classic communications. The concern was that the entangled photons would be overwhelmed by the millions of other light particles present in the fiber optic cables. However, Kumar and his team were able to devise a solution. Through extensive studies of light scattering within fiber optic cables, the researchers identified a less crowded wavelength of light to place their photons. They also implemented special filters to reduce noise from regular Internet traffic. Kumar explained that he and his team conducted a meticulous analysis of light scattering patterns and strategically positioned their photons at a critical point where the scattering effect was minimized.

To validate their method, the team set up a 30-kilometer-long (18.6 miles) fiber optic cable with a photon at each end. They simultaneously transmitted quantum information and high-speed Internet traffic through the cable. The quality of the quantum information was measured at the receiving end while executing the teleportation protocol by making quantum measurements at the mid-point. The results showed that the quantum information was successfully transmitted, even in the presence of busy internet traffic.

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