The question of whether quantum communication could integrate with existing Internet infrastructures has long intrigued scientists. A recent demonstration by American engineers could be a game-changer, showing that quantum teleportation is feasible even on fiber optic cables already used for Internet traffic. This advance sheds new light on the possibilities of fusion between classical and quantum technologies.
Northwestern University engineers were the first to successfully demonstrate quantum teleportation over a fiber optic cable already carrying Internet traffic. Their discovery, published in the journal OPTICALsuggests a new possibility: combining quantum communication with existing Internet cables, thereby simplifying the infrastructure needed for advanced sensing technologies or quantum computing applications.
« This is extremely exciting because no one thought it was possible said Prem Kumar, who led the study at Northwestern University. “ Our work shows how next-generation quantum and classical networks could share a unified optical infrastructure. In summary, it allows us to take quantum communications to the next level. »
Prem Kumar, an expert in quantum communications, is a professor of electrical and computer engineering at Northwestern’s McCormick School of Engineering, where he directs the Center for Photonic Communication and Computing.
The operation of the quantum teleportation
Quantum teleportation is limited only by the speed of light, enabling ultra-fast and secure information sharing between remote users without direct transmission. The process relies on quantum entanglement, a technique where two particles are linked, regardless of the distance between them. Rather than physically transporting particles to transmit information, entangled particles exchange information over large distances without physically transporting it.
« In optical communications, all signals are converted into light “, explained Prem Kumar. “ While conventional signals for classical communications typically involve millions of particles of light, quantum information uses single photons. »
« By performing a destructive measurement on two photons — one carrying a quantum state and the other entangled with another photon — the quantum state is transferred to the remaining photon, which may be very far away said Jordan Thomas, a doctoral candidate in Kumar’s lab and first author of the paper. “ The photon itself does not need to be sent long distances, but its state ends up being encoded on the distant photon. Teleportation allows the exchange of information over great distances without requiring the information itself to travel that distance. »
Find the way to light
Before this study, many researchers doubted the possibility of quantum teleportation in cables carrying classical communications. The entangled photons risked getting lost among the millions of other light particles, a situation comparable to that of a fragile bicycle trying to navigate a tunnel clogged with heavy trucks traveling at high speed.
Prem Kumar and his team nevertheless found a way to protect the delicate photons from heavy traffic. After studying in depth how light scatters in fiber optic cables, they identified a less crowded wavelength to place their photons. Additionally, they added special filters to reduce noise from regular internet traffic.
« We have carefully studied how light scatters and placed our photons at a sensible point where the scattering mechanism is minimized. », Specified the scientist. “ We discovered that we could perform quantum communication without interference from classical channels present simultaneously. »
To test their method, the researchers set up a 30 kilometer fiber optic cable with a photon at each end. They then simultaneously sent quantum information and high-speed Internet traffic through the cable. Finally, they measured the quality of quantum information at the receiving end while running the teleportation protocol by quantum measurements at the midpoint. The researchers found that the quantum information was transmitted successfully, even with Internet traffic passing at high speeds.
« Although many groups have studied the coexistence of quantum and classical communications in fibers, this work is the first to show quantum teleportation in this new scenario », Mentioned Jordan Thomas. “ This ability to send information without direct transmission enables even more advanced quantum applications without requiring a dedicated fiber. »
Of the perspectives future
Prem Kumar plans to extend the experiments over greater distances. He also plans to use two pairs of entangled photons — instead of just one — to demonstrate entanglement exchange, another important step toward distributed quantum applications. Finally, his team is exploring the possibility of performing experiments on optical cables buried in the real world rather than on spools in the laboratory.
« Quantum teleportation has the ability to provide secure quantum connectivity between geographically distant nodes », Prem Kumar concludes. « But many have long assumed that no one would build specialized infrastructure to send particles of light. If we choose wavelengths correctly, we won’t have to build new infrastructure. Classical and quantum communications can coexist. »
Illustration caption: Northwestern engineers have successfully demonstrated quantum teleportation over a fiber optic cable already carrying Internet traffic, introducing the new possibility of combining quantum communication with existing Internet cables.
