Northwestern University engineers have achieved a significant breakthrough by demonstrating quantum teleportation over fiber optic cables that are already carrying Internet traffic. This development suggests the potential to integrate quantum communication with existing infrastructure, potentially easing the requirements for distributed quantum sensing or computing applications.

The research, published in the journal Optica, was led by Prem Kumar, a professor of electrical and computer engineering at Northwestern's McCormick School of Engineering. "This is incredibly exciting because nobody thought it was possible," Kumar stated. He emphasized that this advancement could lead to next-generation networks where quantum and classical communications share a unified fiber optic infrastructure.

Quantum teleportation allows for ultra-fast and secure information sharing between distant users without direct transmission. It relies on quantum entanglement, where two particles are linked regardless of their distance apart. Jordan Thomas, a Ph.D. candidate in Kumar's lab and the paper’s first author, explained that "the photon itself does not have to be sent over long distances, but its state still ends up encoded onto the distant photon."

Previously, many researchers doubted if quantum teleportation could occur within cables also used for classical communications due to potential interference from millions of light particles. However, Kumar's team identified less crowded wavelengths for their photons and utilized special filters to minimize noise from regular Internet traffic.

"We carefully studied how light is scattered and placed our photons at a judicial point where that scattering mechanism is minimized," Kumar said. Their experiments involved sending quantum information through a 30-kilometer-long cable alongside high-speed Internet traffic while maintaining the integrity of the transmitted data.

Thomas noted that "this work is the first to show quantum teleportation in this new scenario," highlighting its significance in advancing more complex quantum applications without requiring dedicated fibers.

Kumar plans to extend these experiments over longer distances and explore real-world applications using inground optical cables. Despite challenges ahead, he remains optimistic about integrating quantum connectivity into existing systems without building specialized infrastructure.

"Quantum teleportation has the ability to provide quantum connectivity securely between geographically distant nodes," Kumar remarked. The study received support from the U.S. Department of Energy under grant number DE-AC02-07CH11359.