In a major R&D breakthrough, researchers from Northwestern University, Boston University (BU), and the University of California, Berkeley (UC Berkeley) have announced their successful development of the world’s first known silicon chip to integrate a photonic quantum system directly into traditional electronic architecture— all fabricated entirely within a commercial semiconductor foundry.
The chip integrates quantum light-generating photonic components together with conventional electronic control circuitry, all within a one-by-one millimeter footprint. This compact design not only enables on-chip generation of quantum light but also incorporates built-in electronic feedback to actively stabilize the optical output in real time.
This photonic-electronic integration allows the chip to produce a consistent stream of entangled photon pairs, a critical requirement for quantum information encoding in photonics-based applications such as secure communications, sensing, and computation.
The successful quantum chip fabrication, most notably, was achieved using standard processes within a commercial semiconductor foundry, thereby underscoring its potential for scalable mass production. Full research findings were published in the July 2025 issue of Nature Electronics.
“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.”
“For the first time, we have achieved monolithic electronic, photonic and quantum integration,” said Northwestern’s Prem Kumar, one of the study’s senior authors. “This is a big deal because it’s not easy to mix electronics and photonics. It was a heroic effort that combined expertise from an interdisciplinary, collaborative team of physicists, electrical engineers, computer scientists, materials scientists and manufacturing experts. Our chip could open doors for not only computing but sensing and communication applications.”
A close-up of the CMOS-integrated quantum chip with built-in feedback stabilization. The self-correcting design ensures stable operation despite temperature and fabrication variations. (Photo courtesy of Anirudh Ramesh/Northwestern University)
A recognized expert in quantum optics, Kumar is a professor of electrical and computer engineering at Northwestern’s McCormick School of Engineering, where he also directs the Center for Photonic Communication and Computing. At the time of the aforementioned research, Ramesh was a Ph.D. candidate in Kumar’s laboratory. He is now employed as a quantum systems validation engineer at U.S.-based quantum computing company PsiQuantum.
Ramesh co-led the study with Danielius Kramnik at UC Berkeley and Imbert Wang at BU. Kramnik, who led the circuit design and electronic integration, is a recent Ph.D. graduate from the laboratory of Vladimir Stojanovíc, an adjunct professor of electrical engineering and computer sciences at UC Berkeley. Wang, who led the photonic device design, is a recent Ph.D. graduate from the laboratory of Miloš Popović, an associate professor of electrical and computer engineering at BU.
Silicon chips offer a promising platform for photonics-based quantum systems due to their capability to be produced using the same high-volume semiconductor manufacturing techniques that already successfully fabricate billions of transistors. However, slight temperature fluctuations, microscopic fabrication inconsistencies, or internally generated heat can entirely destabilize a quantum system. Traditionally, researchers have relied upon the use of bulky external equipment to mitigate such variations — a requirement that has long hindered miniaturization efforts on fully integrated quantum systems.
The concept of generating quantum light in silicon — a key capability in the team’s foundry-fabricated chip — traces back to a landmark study led by Kumar’s laboratory at Northwestern. With its findings published in a 2006 issue of Optics Express, the study was the first to demonstrate that the direction of a concentrated beam of light into specially designed nanoscale channels etched in silicon could naturally produce photon pairs. These photon pairs are inherently linked, thereby allowing them to serve as qubits within photonic quantum systems.
In their latest study, the team integrated tiny ring-shaped channels — each significantly smaller than the width of a human hair — into the silicon chip. When excited by a strong laser source, these circular structures, known as microring resonators, generate photon pairs. To maintain light control, the researchers embedded miniature photocurrent sensors for the continuous real-time monitoring of potential signal drift conditions arising from temperature fluctuations or other environmental disturbances. Upon detecting any such shifts, the sensors trigger on-chip microheaters to perform real-time system adjustments and restore the chip to its optimal operational state.
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.
“Our goal was to show that complex quantum photonic systems can be built and stabilized entirely within a CMOS (complementary metal-oxide-semiconductor) chip,” Kramnik said. “That required tight coordination across domains that don’t usually talk to each other.”
To enable quantum chip fabrication via a standard CMOS semiconductor process, the researchers implemented a strategic co-design approach. The photonic components of the quantum system were built directly into the existing physical structures that are already used by commercial CMOS factories for traditional computer chip manufacturing.
“We pushed the photonics to work within the strict constraints of a commercial CMOS platform,” Wang said. “That’s what made it possible to co-design the electronics and quantum optics as a unified system.”
As quantum photonic systems continue to scale in complexity, such integrated quantum chips may ultimately serve as foundational components for future technologies, ranging from quantum-secure communication networks, precision sensing platforms, and scalable quantum computing infrastructure.
“Quantum computing, communication, and sensing are on a decades-long path from concept to reality,” said Popović, 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.”
This research effort received support from the National Science Foundation, the Packard Fellowship for Science and Engineering, and the Catalyst Foundation. Fabrication of the chip was made possible with contributions from Ayar Labs and GlobalFoundries.
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Source: Northwestern University
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