A recent study led by quantum researchers at the Department of Energy's Oak Ridge National Laboratory proved popular among the science community interested in building a more reliable quantum network.
The study, led by ORNL's Hsuan-Hao Lu, details development of a novel quantum gate that operates between two photonic degrees of freedom - polarization and frequency. (Photonic degrees of freedom describe different properties of a photon that can be controlled and used to store or transmit information.) When combined with hyperentanglement, this new approach could enhance error resilience in quantum communication, helping to pave the way for future quantum networks.
Their work was published in the journal Optica Quantum and was included in the journal's top downloads list for July-September 2024.
"Photons, the smallest packets of electromagnetic energy, are viable carriers of information across quantum networks," said Lu. "Each photon has multiple degrees of freedom - such as path, polarization and frequency - that can carry quantum information. The quantum connection between photons, known as entanglement, enables protocols like quantum teleportation. However, this connection is highly sensitive to environmental conditions, which can introduce errors during transmission."
Through hyperentanglement, which is the entanglement of multiple degrees of freedom between two photons, Lu and his team determined that communication could be more reliably shared.
"Imagine you have a photon that's horizontally polarized, which corresponds to a communication bit value of zero, for example. As it travels through fiber, its polarization could change randomly, introducing errors in communication," Lu said. "The techniques we developed here, when combined with hyperentanglement, have the potential to suppress these errors in a networking task."
Researchers on the project established that this hyperentanglement could be manipulated through a novel quantum gate and used in an application, namely improving the ability to communicate via a quantum network.
Lu's research complements that of his ORNL colleague Alex Miloshevsky in his paper titled, " CMOS photonic integrated source of broadband polarization-entangled photons ." Miloshevsky's paper was also published in Optica Quantum and included on the top downloads list.
"I really appreciate being on the top downloads list," Lu said. "But there's more work to do to get even better."
The next step for this research is to deploy this new technology on ORNL's quantum network.
Funding for this work was made possible through DOE's Advanced Scientific Computing Research program and the Quantum-Accelerated Internet Testbed (QuAInT).
In celebration of the International Year of Quantum Science and Technology in 2025, ORNL continues to empower the pursuit of quantum innovation, advancing world-leading scientific discovery to enable a quantum revolution that promises to transform a vast range of technologies critical to American competitiveness. Click here to learn more about Quantum Science at ORNL.
UT-Battelle manages ORNL for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science . - Mark Alewine
