Researchers have demonstrated a practical approach to weaving quantum communication into existing fiber networks, signaling a meaningful advance toward a functional quantum internet. In a recent Science publication, a team showcased the transmission of quantum signals over standard fiber-optic cables that already carry classical internet traffic, enabling compatibility with current protocols.
Led by Liang Feng of the University of Pennsylvania, the project highlights a shift from isolated laboratory setups to real-world networks. Under his direction, the team introduced a specialized quantum chip dubbed Q-Chip, which carries quantum information alongside conventional data on the same fiber without disturbing the quantum state. This is achieved by appending a classical header—encoded with fiber-laser pulses—to each quantum signal. Routers read the header to route data correctly while preserving the integrity of the quantum information, allowing quantum and classical signals to travel in tandem over a single link.
Q-Chip thus addresses a core challenge: quantum data are highly fragile and can be corrupted by observation or interference. By separating routing information into a robust classical layer, the quantum payload remains shielded from disruption as it traverses networks built for classical data.
The team validated the system over a one-kilometer fiber link owned by Verizon, observing that the quantum signal behaved similarly to classical signals under environmental noise. Disturbances stemming from classical traffic were mitigated, and the quantum information reached its destination securely. These findings imply that quantum data can be transmitted in harmony with prevailing infrastructure, rather than requiring entirely new networks.
Beyond the immediate test, the researchers anticipate that the silicon-based Q-Chip architecture will scale with conventional manufacturing processes, paving the way for mass production. Feng emphasizes that this work marks a foundational step toward launching initial quantum internet capabilities in local and metropolitan networks, signaling a practical trajectory for integrating quantum communication into everyday connectivity.
