Quantum networking may be closer to practical use thanks to engineers at the University of Pennsylvania, who have developed a “Q-chip” capable of transmitting quantum data over existing internet networks.

Figure 1. Quantum Networks Achieved Over Existing Internet Cables.

The team hopes this breakthrough will pave the way for a future “quantum internet” with transformative potential. Figure 1 shows Quantum Networks Achieved Over Existing Internet Cables.

“This is reminiscent of the early days of the classical internet in the 1990s, when universities first connected their networks,” says Robert Broberg, a doctoral student in electrical and systems engineering at Penn and coauthor of the study.

“That connectivity led to transformations no one could have imagined. A quantum internet could have a similar impact.”

Quantum networks function through pairs of entangled particles, where altering one particle instantly affects the other. By harnessing this property, researchers aim to link quantum computers and combine their processing power.

Yet the very nature of quantum entanglement makes building these networks extremely challenging. As Erwin Schrödinger discovered, quantum particles lose their quantum properties when observed, making network calibration a nearly impossible task.

“Conventional networks rely on measuring data to guide it to its destination,” explains Broberg. “In purely quantum networks, you can’t do that, because measuring the particles destroys their quantum state.”

Despite this hurdle, the Penn team demonstrated that their Q-chip can transmit quantum signals over live commercial fiber. They achieved this by coordinating quantum signals with classical signals from ordinary light particles.

“The classical signal moves slightly ahead of the quantum signal,” explains Yichi Zhang, the study’s lead author and a member of Penn’s Materials Science and Engineering faculty.

“The classical ‘header’ works like a train’s engine, with the quantum information following behind in sealed containers,” says Zhang.

“You can’t open the containers without destroying their contents, but the engine ensures the entire train reaches its destination safely.”

The team’s design can automatically correct for noise while transmitting quantum signals using the same addressing and management tools as classical data. This means an entire quantum network could operate on the familiar Internet Protocol (IP) that underpins today’s online world.

“By demonstrating that an integrated chip can manage quantum signals on a live commercial network like Verizon’s—while using the same protocols that run the classical internet—we’ve taken an important step toward large-scale experiments and a practical quantum internet,” says Liang Feng, senior author of the study and MSE professor.

Unlike controlled laboratory setups, commercial optical fibers are exposed to environmental factors such as temperature fluctuations, seismic activity, and vibrations from construction and transportation. To overcome this, the researchers developed an error-correction approach that leverages the classical signals sent just ahead of the quantum ones. Their tests showed the system maintained an inferred accuracy above 97%.

“Because we can measure the classical signal without disturbing the quantum one, we can determine what corrections are needed without directly measuring the quantum state—thus preserving it,” Feng explains.

While the signals cannot be amplified without disrupting quantum entanglement, the team believes that the chip’s silicon-based design will allow for scalable, low-cost production, laying the groundwork for broader quantum networks.

Source: COSMOS

Cite this article:

Priyadharshini S (2025), Existing Internet Cables Successfully Support Quantum Networks, AnaTechMaz, pp.361