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Researchers from the Department of Energy’s Oak Ridge National Laboratory (ORNL), EPB of Chattanooga, and the University of Tennessee at Chattanooga (UTC) have successfully sent an entangled quantum signal via a commercial fiber network with no scheduled downtime. The trial introduced automatic polarization compensation (APC) to stabilize photon-based qubits, offering a step toward a more secure quantum internet. APC employs laser-generated reference signals to recalibrate polarization, managing external factors such as wind or temperature shifts that may disrupt fiber-optic lines.
The demonstration ran for more than 30 hours without interruptions, transferring photons between UTC’s campus node and two EPB quantum network nodes. Joseph Chapman, an ORNL quantum research scientist, noted that many earlier solutions required resetting the network or limiting certain polarization modes.
"One of our goals all along has been to develop quantum communications systems that operate seamlessly for users. This is the first demonstration of this method, which enabled relatively fast stabilization while preserving the quantum signals, all with 100% uptime."
— Joseph Chapman, ORNL
The setup uses entangled photons as qubits, transmitted with their polarization states interlinked. Qubits differ from classical bits by allowing multiple states simultaneously, enabling emerging use cases in secure communication. Here, the team leveraged entanglement-assisted quantum process tomography to track performance. Data showed minimal added noise while APC was active, confirming its readiness for extended runs.
Beyond academic validation, EPB sees this technique as a boost to its commercially available quantum network initiative.
"Working with organizations like ORNL provides valuable feedback for how we can continue to enhance EPB Quantum Network as a resource for researchers, startups, and academic customers."
— David Wade, CEO, EPB
UTC Vice Chancellor for Research, Reinhold Mann, applauded the success and promised ongoing support, noting that the effort raises the university’s profile in quantum information science. The project received backing from ORNL’s Laboratory Directed Research and Development program, the DOE Office of Science’s Advanced Scientific Computing Research program, and the UTC Quantum Initiative.
DOE’s Office of Science is focused on tackling some of the most pressing obstacles of our time. ORNL remains a key contributor, driving new quantum innovations that may transform numerous fields, from secure data networking to advanced scientific research.
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