In a milestone for scalable quantum technologies, scientists from Boston University, UC Berkeley, and Northwestern University have reported the world’s first electronic–photonic–quantum system on a chip, according to a study published in Nature Electronics. The system combines quantum light sources and stabilizing electronics using a standard 45-nanometer semiconductor manufacturing process to produce reliable streams of correlated photon pairs — a key resource for emerging quantum technologies. The advance paves the way for mass-producible “quantum light factory” chips and large-scale quantum systems built from many such chips working together.
“Quantum computing, communication, and sensing are on a decades-long path from concept to reality,” said Miloš Popović, Associate Professor of Electrical and Computer Engineering at BU and a senior author on the study. “This is a small step on that path — but an important one, because it shows we can build repeatable, controllable quantum systems in commercial semiconductor foundries.”
The kind of interdisciplinary collaboration this work required is exactly what’s needed to move quantum systems from the lab to scalable platforms,” said Prem Kumar, Professor of Electrical and Computer Engineering at Northwestern and a pioneer in quantum optics. “We couldn’t have done this without combined efforts in electronics, photonics, and quantum measurement.”
Just as electronic chips are powered by electric currents, and optical communication links by laser light, future quantum technologies will require a steady stream of quantum light resource units to perform their functions. To provide this, the researchers’ work created an array of “quantum light factories” on a silicon chip, each less than a millimeter by a millimeter.
Generating quantum states of light on a chip requires precisely engineered photonic devices — specifically, microring resonators. To generate streams of quantum light in the form of correlated pairs of photons, the resonators must be tuned in sync with incoming laser light that powers each quantum light factory on the chip (and is used as fuel for the generation process). But those devices are extremely sensitive to temperature and fabrication variations, which can push them out of sync and disrupt the steady generation of quantum light.
“Quantum process in real time,” said Anirudh Ramesh, a Ph.D. student at Northwestern, who led the quantum measurements. “That’s a critical step toward scalable quantum systems.”
The extreme sensitivity of the microring resonators, the building blocks for the quantum light sources, is well known and is both a blessing and a curse. It is the reason why they can generate quantum light streams efficiently and in a minimal chip area. However, small shifts in temperature can derail the photon-pair generation process. The BU-led team solved this by integrating photodiodes inside the resonators in a way that monitors alignment with the incoming laser while preserving the quantum light generation. On-chip heaters and control logic continually adjust the resonance in response to drift.
“A key challenge relative to our previous work was to push photonics design to meet the demanding requirements of quantum optics while remaining within the strict constraints of a commercial CMOS platform,” said Imbert Wang, a Ph.D. student at Boston University who led the photonic device design. “That enabled co-design of the electronics and quantum optics as a unified system.”
Because the chip uses built-in feedback to stabilize each source, it behaves predictably despite temperature changes and fabrication variations — an essential requirement for scaling up quantum systems. It was fabricated in a commercial 45-nanometer complementary metal-oxide semiconductor (CMOS) chip platform originally developed through a close collaboration between BU, UC Berkeley, GlobalFoundries, and Silicon Valley startup Ayar Labs, which grew out of research at the two universities. Through the new collaboration with Northwestern, that same manufacturing process now enables not only advanced optical interconnects for AI and supercomputing, but also, as shown in the study, complex quantum photonic systems on a scalable silicon platform.
“Our goal was to show that complex quantum photonic systems can be built and stabilized entirely within a CMOS chip,” said Daniel Kramnik, a Ph.D. student at UC Berkeley who led chip design, packaging, and integration. “That required tight coordination across domains that don’t usually talk to each other.”
As quantum photonic systems progress in scale and complexity, chips like this could become building blocks for technologies ranging from secure communication networks to advanced sensing and, eventually, quantum computing infrastructure.
For more information, contact Miloš Popović at
