Quantum teleportation proves viable on the existing Internet structure

Scientists have teleported quantum data over a live public internet connection, with quantum signals sharing space with high-speed classical traffic. This is the first time quantum teleportation has worked outside of isolated lab conditions. The experiment proves that quantum communication can run on the same fiber that powers the internet today.

Researchers at Northwestern University’s McCormick School of Engineering demonstrated quantum teleportation of a particle’s state over approximately 29 km (18 miles) of optical fiber within an operational internet infrastructure.

This essentially means they transferred the state of a particle without actually moving the particle itself. The signal traveled through 29 km (18 miles) of optical fiber that was already handling heavy internet traffic at 400 gigabits per second.

This study stands out because it’s the first time quantum teleportation has worked over a live internet link with actual data flowing through it. Earlier efforts relied on isolated setups or simulations. In this case, the quantum state was transmitted while the fiber handled classical high-speed data. Everything from streaming to messaging shared the same fiber.

The team combined both signals using wavelength division multiplexing, then tackled the problem of signal noise by routing the quantum data through a lower-interference O-band channel at 1290 nanometers. To keep the quantum signal intact, they also applied ultra-narrow filters and used precise multi-photon detection to reject background noise caused by Raman scattering.

The researchers had to find a way to keep an entangled photon stable while it traveled alongside dense internet traffic. That’s tricky when it’s surrounded by so much digital jargon. Their solution relied on a detailed understanding of how light interacts with the fiber.

By tuning the wavelength and carefully engineering the photon’s journey, the researchers managed to minimize the amount of interference it encountered. They sent entangled photons in opposite directions to a midpoint, where a Bell state measurement (a critical part of the teleportation process) was carried out. This allowed the quantum state to be transferred without any direct transmission of the original particle.

When quantum internet becomes a reality, it will make today’s internet look obsolete by comparison. It’s expected to open the door to technologies we can now barely imagine. Some early possibilities include next-level encryption, machine learning that improves at an unprecedented pace, and the ability to simulate massive, fast-moving systems like the planet’s climate with far greater accuracy than we can now.

The fidelity of this experiment’s quantum teleportation reached close to 90%, well above the previous limit of 66.7%. This was a big victory, showing that the process remains stable even with intense conventional data traffic.

The future quantum internet will use a mix of technologies. This advancement will rely on a spread-out system of nodes and transmission lines. Everything from fiber optics to wireless signals can and will be used to move data between entangled particles.

This experiment also suggests that we won’t need to build a completely new network from scratch. Instead, the quantum layer could ride on top of the infrastructure that already powers today’s web.

References:

¹ Quantum teleportation coexisting with classical communications in optical fiber – Jordan M. Thomas, Fei I. Yeh, Jim Hao Chen, Joe J. Mambretti, Scott J. Kohlert, Gregory S. Kanter, and Prem Kumar – Optica – December 20, 2024 – DOI https://doi.org/10.1364/OPTICA.540362