The dream of a quantum internet—a network that uses the bizarre rules of quantum mechanics to transmit information—has taken an important step toward reality.
Engineers at the University of Pennsylvania have, for the first time, sent quantum signals through commercial fiber-optic cables using the same Internet Protocol (IP) that powers today’s web.
The breakthrough, described in Science, shows that delicate quantum information can travel on the same infrastructure that carries your emails, video calls, and streaming services.
The experiment took place on Verizon’s campus fiber network and relied on a new device the Penn team calls the “Q-Chip.”
This chip is small, integrates classical and quantum data, and most importantly, speaks the same digital language as the modern internet.
That means a future quantum internet could one day expand using the very same systems that already connect billions of people around the world.
Quantum networking relies on a strange phenomenon called entanglement, where two particles become so closely linked that changing one instantly affects the other, even if they are far apart.
Scientists believe that harnessing this property could allow quantum computers to connect, share processing power, and solve problems beyond the reach of today’s most powerful machines.
That could include designing entirely new medicines, building stronger materials, or running advanced AI with much greater efficiency.
But sending quantum information is not easy. Ordinary networks rely on measuring signals as they move along, guiding them toward their final destination.
Quantum signals, however, lose their special properties the moment they are measured. That has made it nearly impossible to scale a true quantum network outside controlled lab environments.
To solve this problem, the Penn team designed the Q-Chip, short for “Quantum-Classical Hybrid Internet by Photonics.” The chip cleverly coordinates regular “classical” signals—ordinary pulses of light—with quantum particles.
The classical signal is sent just ahead of the quantum signal, acting like a train engine pulling quantum cargo sealed in containers.
The engine can be measured and routed safely, while the fragile quantum cargo rides behind untouched. This allows the system to use the same addressing system and packet-switching techniques that run the internet today, all without destroying the quantum state.
Even more impressive, the researchers showed that their chip can automatically correct for the messy conditions of real-world networks.
Unlike carefully controlled lab setups, commercial fiber lines are constantly disturbed by vibrations, weather, or even construction work. These disturbances normally destroy quantum information.
But since any interference affects both the classical “header” and the quantum “cargo” in the same way, the team can measure the classical signal and apply the right correction to the quantum signal—without ever opening it. This preserves its fragile quantum state.
In their tests, the Penn engineers connected two buildings about a kilometer apart using Verizon’s fiber network. The system maintained transmission fidelities above 97 percent, meaning nearly all the quantum information survived the trip intact.
Because the chip is made from silicon using standard fabrication methods, it could be mass-produced, allowing the network to scale quickly. Expanding it would simply require making more chips and plugging them into existing fiber infrastructure.
The researchers see this as a turning point, though they acknowledge that many challenges remain. One of the biggest is distance. While classical internet signals can be amplified and sent across oceans, quantum signals cannot yet be copied or boosted without destroying their entanglement.
Other groups have demonstrated long-distance “quantum key distribution” for ultra-secure communication, but those systems are not powerful enough to connect actual quantum processors. A true quantum internet will require entirely new technologies to overcome this hurdle.
Still, the Penn team’s demonstration is a critical early milestone. “By embedding quantum information in the familiar IP framework, we showed that a quantum internet could literally speak the same language as the classical one,” said Yichi Zhang, a doctoral student and first author of the study. Senior author Liang Feng added, “By showing that an integrated chip can manage quantum signals on a live commercial network, and do so using standard internet protocols, we’ve taken a key step toward scaling this technology.”
For the researchers, the moment feels much like the early days of the classical internet in the 1990s, when universities first began linking their local networks.
Back then, few could have predicted the revolutionary changes the internet would bring to society. The scientists believe the same could be true for quantum networking: today’s small experiments may eventually grow into a world-changing technology.
