Researchers at Northwestern University, Boston University (BU) and the University of California, Berkeley (UC Berkeley) have built a photonic quantum system into a traditional electronic chip. The chip was fabricated in a commercial semiconductor foundry, pointing to its ability to manufactured for large-scale production. Reportedly the first of its kind, the silicon chip combines both the quantum light-generating components with classical electronic control circuits — all packed into an area measuring just a single square millimeter. The chip is able to generate quantum light and keep it stable using its built-in smart electronic system. The photonic-electronic integration allows the single chip to reliably produce a stream of photon pairs — basic units that encode quantum information — required for light-based quantum communication, sensing, and processing. The work builds on a previous demonstration of quantum light generation in silicon which showed that shining a concentrated beam of light into tiny, appropriately designed channels etched in silicon naturally generates entangled photon pairs. In the new study, the team integrated these tiny, ring-shaped channels — each much smaller than the thickness of a human hair — into the silicon chip. When a strong laser shines into these circular channels, called microring resonators, it generates photon pairs. To control the light, the team added photocurrent sensors, which act like tiny monitors. If the light source drifts due to temperature fluctuations or other disturbances, the sensors send a signal to a tiny heater, which adjusts the photon source back to its optimal state. A packaged circuit board containing the chip placed under microscope in probe station during an experiment. The first-of-its-kind silicon chip combines both the quantum light-generating components (photonics) with classical electronic control circuits — all packed into an area measuring just one millimeter by one millimeter. Courtesy of Northwestern University/Anirudh Ramesh. “Quantum experiments in the lab usually need big, bulky equipment, which requires pristine, clean conditions,” said Northwestern’s Anirudh Ramesh, who led the quantum measurements. “We took many of those electronics and shrunk them down onto one chip. So, now we have a chip with built-in electronic control — stabilizing a quantum process in real time. This is a key step toward scalable quantum photonic systems.” Because the chip uses built-in feedback to stabilize itself, it behaves predictably despite temperature changes and fabrication variations — an essential requirement for scaling up quantum systems. It also bypasses the need for large external equipment. To ensure their complex quantum chip could be manufactured using a standard CMOS process, the scientists adopted a clever design strategy. They built the photonic components directly into the existing structures commercial CMOS factories already use to manufacture computer chips. “We pushed the photonics to work within the strict constraints of a commercial CMOS platform,” said BU researcher Imbert Wang. “That’s what made it possible to co-design the electronics and quantum optics as a unified system.” As quantum photonic systems grow in scale and complexity, these integrated quantum chips could become the building blocks for technologies ranging from secure communication networks to advanced sensing and, eventually, quantum computing infrastructure. “Quantum computing, communication and sensing are on a decades-long path from concept to reality,” said Miloš Popovic, an 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 research was published in Nature Electronics (www.doi.org/10.1038/s41928-025-01410-5).