Researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL) have achieved a scientific breakthrough by developing a new device that couples essential quantum photonic features on a sole computer chip, a significant move towards realizing a functional quantum internet. According to a publication in Optica Quantum, the study brings quantum computing that harnesses photons to create qubits, and for information storage and transmission, closer to mainstream application. Joe Lukens, ORNL associate professor and senior author, told Oak Ridge National Laboratory, "We’re not the first to put any one of these elements on a chip, but we’re the first to put these specific capabilities on a single one."
The innovation lies in the chip's ability to create and entangle qubits which are qubits so intertwined that they retain shared properties even when separated, moreover, this marks a leap towards standardizing production and achieving quantum network scalability. Alexander Miloshevsky, an ORNL postdoctoral research associate and study co-author stated, “If we can mass produce a chip that has all the components we need to generate the necessary polarization entanglement, then it becomes a matter of plugging the chips into a network without having to buy and align all these specialized tabletop components.” The chip also can utilize current fiber-optic networks, thus circumventing the prohibitive prices associated with network infrastructure overhaul.
Central to the device's operation are microring resonators, enabling the generation of entangled photon pairs, and polarization splitter-rotators which filter incoming light into different paths based on polarization – a key to direct generation of broadband polarization entanglement. Researchers highlighted the chip's impressive feat showing over 116 distinct channels, with more than 100 channels demonstrating high fidelity, which they described as a "record number." Compatibility with existing fiber-optic networks simplifies integration into traditional communication systems, allowing use with conventional telecom components.
Commenting on the potential for hyperentangled qubits, Lukens added, "The more degrees of freedom we can use to entangle and encode these qubits, the more information we can potentially pack in," illustrating the device's capacity for robust and high-density information transmission key to pioneering hyperentanglement where qubits are entangled in multiple ways, say polarization and color. With continued research and optimization, this chip design contributes to building the essential components needed for a broader quantum internet infrastructure. "All of these studies are pieces of a larger picture that eventually gets us to a quantum internet," Lukens told Oak Ridge National Laboratory.
Support for this research came from various sources, including DOE’s Advanced Scientific Computing Research program, the National Science Foundation, and the Air Force Research Laboratory. As part of the International Year of Quantum Science and Technology in 2025, ORNL remains focused on advancing quantum innovations critical to bolstering American technological leadership and addressing major contemporary challenges.
