This achievement marks a significant step toward a functional quantum internet, which promises enhanced security and efficiency compared to current networks.

Figure 1. Quantum Networking Breakthrough: Entangled Photons Transmit Uninterrupted for 30+ Hours.

To ensure stable signal transmission, researchers implemented automatic polarization compensation (APC), a technique that corrects shifts in polarization—the orientation of a light wave's electric field. The system used laser-generated reference signals and an advanced method called heterodyne detection to continuously monitor and adjust polarization in real time. Figure 1 shows Quantum Networking Breakthrough: Entangled Photons Transmit Uninterrupted for 30+ Hours.

By employing APC, the team effectively mitigated environmental disruptions such as wind and temperature fluctuations, which can interfere with quantum signals traveling through fiber-optic cables.

Overcoming Signal Interference for Seamless Communication

“Our goal has always been to develop quantum communication systems that function seamlessly for users,” said Joseph Chapman, a quantum research scientist at ORNL and the study's lead. “This is the first demonstration of this method, enabling rapid stabilization while preserving quantum signals—all with 100% uptime. That means users on either end experience no signal interruptions or need for scheduled downtime.”

This breakthrough enabled continuous, uninterrupted quantum signal transmission for more than 30 hours between a node on the University of Tennessee Chattanooga campus and two other EPB quantum network nodes, each approximately half a mile away. The UTC node housed an entangled-photon source developed by ORNL quantum research scientist Muneer Alshowkan.

Quantum Qubits: The Key to Future Computing

Quantum computing relies on quantum bits, or qubits, to store and process information. Unlike classical binary bits, which represent either 0 or 1, qubits leverage quantum superposition, allowing them to exist in multiple states simultaneously. This unique property enables complex calculations far beyond the reach of traditional computing.

In their study, researchers at ORNL used photons—light particles—as qubits, transmitting polarization-entangled qubits in photon pairs via quantum entanglement distribution. Because entangled qubits are intrinsically linked, changes to one immediately affect the other, regardless of distance. This phenomenon enables quantum teleportation, allowing information to be transferred without physically traveling through space. Together, entanglement distribution and quantum teleportation lay the foundation for future quantum networks.

Tackling Disruptions in Fiber-Optic Quantum Networks

Qubits encoded in photons can be transmitted over existing fiber-optic cables, making them a viable medium for quantum networking. However, environmental factors such as wind, moisture, and temperature fluctuations can disrupt photon polarization, causing signal interference. The ORNL team, led by Joseph Chapman, sought a solution to stabilize polarization while maintaining network performance at maximum bandwidth.

“Most previous solutions didn’t work for all polarization types and required trade-offs, like periodically resetting the network,” Chapman explained. “But users need a continuously running network. Our approach compensates for any polarization shifts without requiring periodic shutdowns.”

Testing and Fine-Tuning the Quantum Process

To validate their method, Chapman and Muneer Alshowkan employed entanglement-assisted quantum process tomography. This technique estimated the properties of the quantum channel—such as fiber-optic cables with automatic polarization compensation (APC)—to detect and correct polarization shifts in real time. When APC was enabled, transmissions remained stable with minimal additional noise.

“An experienced musician with a good ear can tell when two instruments are out of tune,” Chapman said. “In our APC system, we use a laser to achieve the same effect with our reference signals.”

Patent Pending: What’s Next for Quantum Networking?

Chapman has applied for a patent on the polarization stabilization method. The next phase of research will focus on increasing bandwidth and expanding compensation range to enhance performance under diverse conditions.

“Collaborating with ORNL provides valuable insights into improving the EPB Quantum Network as a research, startup, and academic resource,” said David Wade, CEO of EPB. “Since launching a commercially viable quantum network, we’ve been working to position Chattanooga as a hub for quantum innovation and investment.”

“We’re thrilled to be part of this successful collaboration,” said Reinhold Mann, vice chancellor for research at UTC. “This partnership not only advances quantum information science but also enhances hands-on learning opportunities for our students.”

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025),Quantum Networking Milestone: Entangled Photons Maintain Transmission for Over 30 Hours, AnaTechmaz, pp. 203