4/24/2026 Jeni Bushman
Researchers from The Grainger College of Engineering have demonstrated a new method for converting single photons. Their device has implications for quantum internet infrastructure and hybrid quantum systems.
Written by Jeni Bushman
Researchers from The Grainger College of Engineering have demonstrated a new method for converting single photons. Their device has implications for quantum internet infrastructure and hybrid quantum systems.
A crucial step towards building scalable quantum networks is quantum frequency conversion (QFC), a technique that changes the frequency of single photons while preserving the quantum state. Current methods for QFC are hampered by low efficiency and large power requirements. But a new approach developed by the lab of Illinois Grainger Engineering professor Kejie Fang uses an on-chip translator to achieve highly efficient bidirectional quantum conversion, bringing the field closer to practical quantum networks.
As reported in Nature Communications, Fang’s research group created a nanophotonic waveguide made of indium gallium phosphide (InGaP) that converts photons bidirectionally between telecom and visible wavelengths. The resulting device acts as a translator between wavelengths and simultaneously protects the quantum information being transported.
“Quantum frequency conversion is crucial for quantum networking, but currently there are no integrated devices for quantum frequency conversion with high efficiency, low noise, and broad bandwidth,” Fang said.
The Illinois Grainger engineers’ technology uses a nonlinear optical process for efficient light conversion and incorporates a programmable nanoheater array to mitigate small imperfections that can inhibit the conversion process. Its high efficiency, low power requirements, broad bandwidth, low error rate, and flexible wavelength tuning improve upon existing QFC systems.
Going forward, Fang’s group will continue innovating to further reduce pump power and noise. The Illinois Grainger engineers are hopeful that future iterations of the device could enable quantum networks of atomic quantum information processors connected with optical fibers.
Illinois Grainger Engineering Affiliations
Kejie Fang is an Illinois Grainger Engineering associate professor in the Department of Electrical and Computer Engineering. He is affiliated with the Holonyak Micro and Nanotechnology Lab, the Illinois Quantum Information Science and Technology Center and the Department of Physics.