Why it matters
Current quantum computers are severely limited by heat generation and wiring — scaling to the million qubits and wires needed for practical applications would produce thousands of watts of heat, about orders of magnitude times more than existing cooling systems can handle.
The breakthrough
Assistant Professor Chris Anderson from the Department of Materials Science and Engineering at The Grainger College of Engineering, University of Illinois Urbana-Champaign, has earned a Defense Advanced Research Projects Agency (DARPA) Young Faculty Award for his research on strontium titanate (STO) optical modulators.
By the numbers:
- 20x stronger electro-optic effect than current industry standard lithium niobate.
- 400x boost in interconnect performance potential.
- Two orders of magnitude less thermal conduction than traditional cables.
- Three orders of magnitude greater bandwidth than coaxial cables.
How it works
Anderson's approach replaces bulky microwave cables with ultra-thin optical fibers that carry quantum information as light signals rather than electrical currents. These fibers already find use in standard communications and connect computers in data centers, but harnessing the potential of optics at low temperatures remains a challenge. Anderson’s development of new specialized materials for low temperature quantum applications unlocks massive scaling of cryogenic quantum systems.
What Anderson says
"We're essentially solving the one of the fundamental problems that makes large scale quantum computers impossible today," Anderson said. "By discovering that strontium titanate is the world’s most tunable optical material at cryogenic temperatures, we can create interconnects that are not just incrementally better, but orders of magnitude more efficient that before. This is the difference between quantum computers remaining laboratory curiosities and becoming practical machines that solve real-world problems."
The big picture
The research, dubbed "Quantum-paraelectric STO Optical Links for Egress and Ingress at Low-temperature" (Q-SOLEIL), addresses critical infrastructure needs for:
- Fault-tolerant quantum computers.
- Rapid single flux quantum computing.
- Radio astronomy applications.
- Particle physics research
These items would all benefit from optical wiring in low temperature environments.
What's next
Building on previous support from Google Quantum AI, Anderson's team will fabricate and test the first thin-film STO photonic devices at 4 Kelvin, with plans to extend to millikelvin environments.
Between the lines
The DARPA recognition validates that optical interconnects represent a paradigm shift for thermal management in low temperature environments — potentially the key to making quantum computing commercially viable rather than just scientifically impressive.
Illinois Grainger Engineering Affiliations
Chris Anderson is an Illinois Grainger Engineering assistant professor in the Department of Materials Science and Engineering and is affiliated with both the Department of Physics and the Department of Electrical and Computer Engineering. He is a member of the Illinois Quantum Information Science and Technology Center, the Materials Research Laboratory and the Holonyak Micro and Nanotechnology Lab.