Researchers at Northwestern University have reached a major milestone by successfully demonstrating quantum teleportation using a fiber optic cable that also carries regular Internet traffic. This innovation simplifies the potential integration of quantum and classical communications, offering a path to a common infrastructure. The experiment proved that quantum information can be transmitted along with ordinary data without interference, promising more efficient and secure communication technologies.

Groundbreaking discovery in quantum teleportation

Northwestern University engineers have achieved a revolutionary milestone by successfully demonstrating quantum teleportation over a fiber optic cable that currently carries regular Internet traffic. This breakthrough shows that quantum communications can be integrated with existing Internet infrastructure, eliminating the need for dedicated networks and simplifying the technology needed for quantum computing and sensing applications.

The team’s findings will be published today (December 20) in the journal Optical.

“This is incredibly exciting because no one thought this was possible,” said Northwestern’s Prem Kumar, who led the study. “Our work points the way to next-generation quantum and classical networks sharing a unified fiber optic infrastructure. Fundamentally, this opens the door to taking quantum communications to a new level.”

An expert in quantum communications, Kumar is a professor of electrical and computer engineering at Northwestern’s McCormick School of Engineering, where he directs the Center for Photonic Communications and Computing.

Mechanics of quantum teleportation

Limited only by the speed of light, quantum teleportation can make communication nearly instantaneous. The process works using quantum entanglement, a technique in which two particles bond regardless of the distance between them. Instead of particles physically traveling to transmit information, entangled particles exchange information over long distances without physical transfer.

“In optical communication, all signals are converted into light,” Kumar said. “While conventional signals for classical communication often involve millions of particles of light, quantum information uses individual photons.”

Innovations in Photon Management

Before Kumar’s new research, the conventional wisdom was that individual photons would get lost in the cables containing millions of light particles that carry classical communication. This is like a flimsy bicycle trying to pass through a crowded tunnel where heavy trucks are speeding by.

But Kumar and his team found a way to help sensitive photons stay away from heavy traffic. After conducting in-depth studies of how light is dispersed in fiber optic cables, researchers found a less crowded wavelength of light to accommodate photons. They then added special filters to reduce noise from normal internet traffic.

“We carefully studied how light is scattered and placed our photons at a legal point where this scattering mechanism is minimized,” Kumar said. “We found that we can achieve quantum communication without the interference of simultaneously existing classical channels.”

Future prospects and expansion of the experiment

To test the new method, Kumar and his team laid a 30-kilometer fiber optic cable with photons at both ends. They then simultaneously sent quantum information and regular internet traffic through it. Finally, they measured the quality of quantum information at the receiving end during the execution of the teleportation protocol by performing quantum measurements at the midpoint. Researchers found that quantum information can be transferred successfully even in heavy internet traffic.

Kumar then plans to expand the experiments to greater distances. It also plans to use two pairs of entangled photons instead of a single pair to demonstrate entanglement switching, another major milestone leading to distributed quantum applications. Finally, his team is exploring the possibility of conducting experiments on real underground optical cables rather than coils in the laboratory. But although there is a lot of work to be done, Kumar is optimistic.

“Quantum teleportation has the potential to provide a secure quantum connection between geographically distant nodes,” Kumar said. “But many people have long believed that no one could build a special infrastructure for sending light particles. If we tune the wavelengths correctly, we won’t need to build new infrastructure. Classical communication and quantum communication can coexist.”