The world would look radically different without rulers and measuring tapes that fit into a pocket. Carpenters, fashion designers and engineers rely on these trusty tools to check the size of everything from a wooden board to a fabric swatch. But physicists who work with light lack that same convenience for one of the basic measurements of their craft. They routinely need to measure and compare the frequencies—colors—of the light waves they are using. To date, they have lacked a similarly pocket-sized tool for routine measurements, and they make do with cumbersome equipment that crowds their lab space and is far from portable.An artistic visualization of a novel process that forms an optical frequency comb, which researchers can use to perform a variety of precision measurements. During the formation process, two lasers circulate in a small resonator and spread out, forming the blue and red curves, while also interacting to produce the purple curve. All three curves merge into a comb that provides a pristine ruler for measuring light, represented by the purple lines at the top of the image. (Credit: Carl De Torres at the Optics Lab)

The standard tool for measuring the frequency of light is called an optical frequency comb. This device produces a rainbow of different frequencies of light, all spaced at regular intervals like the tick marks on a measuring tape. Frequency combs let researchers measure the difference between distinct frequencies and are crucial for many experiments and measurements that use light. Large lab setups have proven the usefulness of frequency combs by enabling the creation of the most precise clocks in the world—atomic clocks—as well as many other applications. Researchers have been seeking smaller optical frequency combs both to make their lives easier and to provide the basis for new light-based technologies. For instance, portable atomic clocks could help map underground variations in mineral deposits and enable navigation systems that don’t rely on GPS satellite signals.

JQI researchers have worked with an international collaboration to develop and demonstrate a new type of frequency comb. The new design eliminates the need for bulky equipment while also making it simple to adapt a single device to a variety of practical measurement tasks. The researchers described the advances behind their frequency comb and its performance on common tasks in an article published Sept. 30, 2026, in the journal Nature. To demonstrate the adaptability of their compact device, they used it with a variety of light sources to test its capability at tasks that are the bread and butter of optical frequency combs.

The result builds on a decade of research that JQI research scientist Grégory Moille and JQI Fellow and Co-Director Kartik Srinivasan have put into miniature optical frequency combs that fit on a portable chip. Their new approach grew out of a partnership with a team led by Miro Erkintalo, who is a researcher at the University of Auckland (UoA) in New Zealand and the Dodd-Walls Centre for Photonic and Quantum Technologies, to explore a new way to make optical frequency combs. Using the new approach, the team, including additional colleagues at the University of Maryland at Baltimore County (UMBC), the University of California at Santa Barbara (UCSB), AV Incorporated and the Air Force Research Laboratory (AFRL), has made an optical frequency comb that performs as well as the older behemoth tabletop versions but takes up a fraction of the lab space.

“Though we have been working on chip-integrated optical frequency combs for many years, their control and stabilization—essential for many applications—has often been complicated and difficult,” says Moille, the first author on the paper who is also an associate of the National Institute of Standards and Technology (NIST). “With this new approach, we finally see a viable path for their use in deployable atomic timekeeping, which is one of their most demanding and important applications.”

Two Lasers Are Better Than One

The new optical frequency comb relies on a phenomenon called parametrically driven cavity solitons (PDCSs), first predicted in 2023 by a team led by Erkintalo. PDCSs involve circulating light from two lasers around a tiny ring, called a microresonator. If the ring is the right shape and researchers inject light into it in just the right way, then the circling light interacts with itself via the material comprising the ring and generates a string of pulses that researchers can use as a frequency comb. PDCS-based combs themselves build on nearly two decades of research into frequency combs using a single laser injected into a microresonator on a chip, but prior attempts haven’t succeeded at freeing chip-based techniques from bulky equipment and getting it reliably deployed outside labs.

The collaboration began after Moille and Srinivasan, who is also a NIST Fellow, learned about Erkintalo and his colleagues’ prediction, and the two groups teamed up to make it a reality. They reported on their experiments producing PDCSs in 2024 and showed that they had unlocked a way to measure a range of frequencies that were previously inaccessible. 

That first PDCS demonstration proved the concept and explored the underlying physics but left much of the research into how it performed at practical tasks for future experiments. In particular, the frequency comb produced multiple overlapping sets of frequency lines. The overlap made the comb almost impossible to use, like a ruler misprinted with multiple sets of tick marks.

In the new paper, the researchers combined the PDCS approach with a synchronization technique that Srinivasan, Moille and their colleagues previously demonstrated can stabilize optical frequency combs. The combination of techniques locked all the frequency lines into alignment—a process called self alignment—and provided a pristine ruler with just a single set of tick marks for measuring frequencies.

Moille and Srinivasan nicknamed this particular way of driving light in a resonator a SParCS (self-aligned parametrically-driven cavity soliton). The new SParCS-based combs have unique advantages derived from the way they distribute the power carried by light at different frequencies throughout the comb. Past approaches used a single laser to create a comb that spread out on either side of the laser’s frequency. Those additional frequencies—the comb teeth—have less power the further they are from the central frequency, and they become less sharply defined towards the edges. 

In contrast, researchers can select two lasers at distinct frequencies to create a comb for a particular task, and the two lasers used in the PDCS technique serve as bookends for the comb with the additional teeth forming in the space between. This produces more precise teeth throughout the comb and concentrates the power toward the edges, which are often the critical comb teeth for many practical measurements.

In particular, measuring the exact value of a frequency isn’t possible if you don’t know how far the comb is from zero frequency—a value called the zero-frequency offset. Physicists must find the offset for each comb, since small idiosyncrasies in the fabrication of every resonator makes each comb a little different.

The edge teeth are generally essential for determining the zero-frequency offset for a given comb. There is a standard method for finding it, which earned its creators the 2005 Nobel Prize in physics, but combs must meet a crucial requirement for it to work: One of the teeth must be at approximately twice the frequency of a lower-frequency tooth. Physicists use the same language as musicians and call such a span of frequencies an octave. In practice, teeth at the edge of an octave are going to be at or near the comb’s edge, and if they are too weak or unstable, researchers need additional bulky equipment to find the offset.

The team’s ability to select their two laser frequencies, and thus the edge teeth, let them ensure that the comb spans an octave and that the critical edge teeth are easy to work with—making the process of setting up experiments considerably easier and quicker.

Even though the new approach uses twice as many lasers to create a comb, it still makes the overall setup smaller than prior attempts. Other approaches generally have to add a second laser anyway, along with a host of other equipment, to amplify the edge teeth to be strong enough to use in experiments. The new approach eliminates the need for complex, lab-scale equipment and provides a clear path toward devices that are easy to deploy outside a lab.

Running the Comb Through Its Paces

After producing a pristine comb, the team turned toward demonstrating the convenience and versatility of their approach by performing a variety of common measurement tasks. Frequency combs enable diverse measurement techniques by allowing researchers to link two frequencies, to detect subtle fluctuations of frequencies, and to produce light at a very stable frequency. 

In particular, the team wanted to show that SParCS-based combs can act as a perfect frequency gearbox that serves as a link between two frequencies to keep them locked together, similar to how gears coordinate rotations even when they are at different speeds. Essentially, the comb can not only help researchers measure the difference between two frequencies but can also serve as a bridge that locks the spacing in place. Researchers can lock a laser to a particular tooth, establishing a fixed relationship between their laser and the other teeth in the comb. This lets teeth at other frequencies reflect the stability, or conversely the fluctuations, in that laser. If you lock the comb to a very stable laser, it provides stability to teeth at other frequencies, or if your attached laser fluctuates, you can detect that at another frequency that is easier to measure.

The group partnered the comb with various frequencies of light from different sources to demonstrate that a simple swap of lasers could allow the single device to perform tasks that are useful for performing different types of measurements. The tasks drew on the unique hardware and expertise provided by the members of the collaboration.

First, they used the comb to link microwaves, which oscillate at billions of cycles per second, to optical light waves, which oscillate at hundreds of trillions of cycles per second. This sort of portable comb could improve frequency measurements in many devices that measure light frequencies or use light to measure distances, including the lidar used in self-driving cars. The microwaves partnered with the comb let them better pin down the frequency of the teeth, which can allow the comb to make precise frequency measurements or produce stable optical frequency sources.

They then turned their attention to performing the opposite process—linking optical light to microwaves—using the same device. When the comb works in this direction, it has the extra advantage that it naturally decreases the amount of random fluctuations—noise—in the microwaves.

They demonstrated links in this direction through two tasks that frequency combs are used for in different measurements—monitoring light in atomic clocks and the production of microwaves with little noise.

In an atomic clock, the waves in laser light serve as rapid ticks marking time. The laser is made incredibly stable by keeping it tied to the behavior of atoms, but the waves that interact with the atoms oscillate so fast that no electronics can track their fluctuations. A comb is used to transfer the stability of the optical light to a microwave signal that carries the same long-term stability. Those microwaves can then be used by the clock’s electronic systems to track time.

Moille used a device called a “stable atomic clock reference” that was supplied by his colleagues at AFRL, to show how the comb performed at this essential role in an atomic clock. The experiment demonstrated that using the optical light with their comb produced stable microwaves, which are needed to run an atomic clock. They showed that they could use these microwaves to measure the original light frequency, which was oscillating several hundred trillion times per second, to within about a hundred thousand oscillations per second of the value the atoms should produce.

Producing microwaves without much noise is also useful for other measurements outside of atomic clocks. For instance, lowering the noise of microwaves can improve measurements of distance by radar systems. So Moille also swapped in a laser, called a “low-noise laser reference,” that was produced using a specialized chip supplied by their colleagues at UCSB. The experiment demonstrated that using light from a low-noise laser with their comb produced ultra-pure microwave frequencies.

To judge the results, the group also attached all three sources—the two optical sources supplied by colleagues and the microwave source—to their standard tabletop comb system for comparison. They found, to the levels they could check in the experiment, that their small chip produced the same frequencies and generally lived up to its large predecessor in terms of its stability and noise.

“With SParCS, we have a substantially different comb generation process than has been shown previously, and it was important to verify that regardless of how the comb is generated, it can perform its essential functions well,” Srinivasan says. “We're always basically saying, how well are we doing relative to the existing technology? We were very happy to find that our SParCS comb is indeed working well.”

The SParCS approach did more than live up to its massive forebears; it also made it easy for the team to adapt the frequency comb to different applications. Moille used the same device in all the demonstrations. This contrasts with previous on-chip demonstrations, which required a specially tailored microcomb for a given application.

Moille says that performing one of these tasks with a small frequency comb would previously require a team of several people working for weeks or months to get practical results. By comparison, the new experiments were much easier, with him easily swapping in the different light sources supplied by his collaborators. 

“As experimentalists, this new optical frequency comb has simplified much of our work,” Moille says. “The system made it so easy that you actually have only one operator at a time doing each application.” 

The adaptability of the comb also allows the team to compensate for variations, decreasing the demand for accuracy when fabricating combs. This flexibility could make the combs more practical for mass production and integration into products. The convenience also lets the team spend more time performing experiments instead of needing to sift out functional devices from several fabrication attempts and then spend additional time fine-tuning the working ones to get experimental results.

The group demonstrated this robustness by performing measurements using devices made with several different layouts and showed that they could still produce useful results with simple adjustments to their experiments. Moving forward, the team wants to further refine the devices and explore their properties to see how far they can push their performance, such as by making combs that cover larger frequency ranges. Eventually, they hope they may even be able to make the approach work with a single laser feeding into both sides of the comb. Meanwhile, they are using the combs as tools in other experiments.

“Our lab, as of 18 months ago, was 90% dedicated to the typical approach of pumping in the center and then extending out to the edges,” Srinivasan says. “We've now switched all these experiments to focus on the new SParCS approach. Within the last year, we’ve been able to stabilize more than ten times the number of microcombs than we had across all the preceding years combined, and that’s why we feel so strongly that this approach has a lot of potential going forward.”

Original story by Bailey Bedford: New Chip-Based Frequency Combs Demonstrate Potential for Portable Atomic Clocks | Joint Quantum Institute

In addition to Moille, Erkintalo, and Srinivasan, co-authors of the paper include UMBC graduate student Pradyoth Shandilya; UMBC professor Curtis Menyuk; NIST research scientist Jordan Stone; JQI graduate student Shao-Chien Ou; UoA professor Zongda , UCSB graduate students Mark Harrintong and Kaikai Liu; UCSB professor Daniel Blumenthal; River Beard from AFRL and AV Incorporated; and AFRL research physicists Robert Rockmore and Sean Krzyzewski. 

Adil Hassam

Professor Emeritus Adil Hassam died on September 30, 2026. 

Hassam was a distinguished theoretical plasma physicist whose research advanced understanding of plasma confinement, magnetohydrodynamics, controlled thermonuclear fusion, and solar-terrestrial plasmas.

Adil Hassam was honored as the department's Outstanding Advisor in 2015.

He earned his B.S. and M.S. degrees in physics from the Massachusetts Institute of Technology and his Ph.D. in astrophysical sciences from Princeton University.  He joined the University of Maryland in 1978 as a postdoc and rose through the ranks to full professor, while building a long and productive career as a researcher, mentor, and teacher. His work on magnetic and centrifugal confinement contributed to the broader effort to develop practical fusion energy, and he published extensively in plasma physics and related fields. A Fellow of the American Physical Society, Hassam was also recognized for his commitment to teaching and mentoring students. In 2015, he was named an outstanding graduate advisor in the Department of Physics. 

Hassam was a devoted and talented classroom teacher, consistently receiving superlative praise from students, e.g., Professor Hassam was a phenomenal professor, and he should teach all courses always; The teaching style was flawless; and I DONT KNOW HOW IT COULD GET BETTER.

Through his scholarship, collegiality, and dedication to physics, he made lasting contributions to the University of Maryland community and to the field of plasma physics.

Services will be held on October 7 in Carrollton, TX.

A team led by faculty at the Duke Quantum Center (DQC), in collaboration with researchers at the JQI, has used a small number of atoms to simulate an aspect of the extreme physics at play in modern particle colliders and in the chaotic environment that existed shortly after the big bang.

This approach, described in a paper published in the journal Nature Physics on Sept. 23, 2026, demonstrates the viability of trapped-ion quantum computers to begin probing fundamental questions about the universe. The experiment emulates a phenomenon called string breaking in which two connected fundamental building blocks of matter stretch apart, eventually creating so much energy that new particles “pop into existence” when the connection snaps.  

“Quantum computer simulations provide the best platform to investigate complex questions like matter formation, short of having witnessed the big bang itself,” says Christopher Monroe, a professor of electrical and computer engineering and physics at Duke and a College Park Professor of Physics at the University of Maryland (UMD), who led this research. “These findings signal a marked development in the quantum science field and open new avenues for us to understand string-breaking dynamics.”

This research was conducted by an international collaboration that also included researchers working at Oxford University, the California Institute of Technology, Cornell University and KU Leuven. The results join two similar published findings, led by other research teams in the field, which simulated the same phenomenon on different quantum computer platforms.

"This beautiful experiment builds on an earlier collaboration with Chris Monroe, in which we demonstrated the closely related phenomenon of confinement,” says JQI Fellow Alexey Gorshkov, who is also a theoretical physicist at the National Institute for Standards and Technology, a Fellow of the Joint Center for Quantum Information and Computer Science (QuICS) and a Senior Investigator at the National Science Foundation Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS). “My graduate student Fangli Liu was the one who first got me interested in simulating high-energy physics with trapped-ion chains. Bringing together experimentalists and theorists with different areas of expertise has been incredibly rewarding."

The Building Blocks of Matter

The fundamental building blocks of matter, quarks, only exist when bound together inside particles such as protons and neutrons. They are about a billion times smaller than an atom and can’t currently be observed directly. Pairs of these tiny, charged particles are held together by a force that acts like a taut string; quarks want to stick together, and it takes quite a bit of energy to pull them apart. 

But once they are forced apart, the energy built up in their connection can be enough to create more charged particles. When this happens, the string snaps, leaving two or more pairs of particles rather than one. This process requires so much energy, however, that it only happens in extreme environments like the Large Hadron Collider or the aftermath of the big bang. 

In the new study, the team successfully observed analogous string-breaking dynamics on a trapped-ion quantum platform. Quantum simulators, with their high degree of controllability, can be programmed to recreate the real-world processes occurring at the atomic or even subatomic quantum scales.

“Working at the intersection of quantum simulation and high-energy physics is incredibly exciting,” said Arinjoy De, the first author on the paper and a former JQI and Duke graduate student who now works at QuEra Computing. “By simulating quark confinement and string-breaking phenomena in a controlled lab environment, we're opening up new pathways for experimental investigations into the behavior of matter at its most fundamental level.”

How the Simulation Worked

To perform the simulation, the team encoded a string-breaking model into a chain of 13 trapped ions. Using precisely controlled laser beams, researchers were able to tune the interactions among the ions. These interactions effectively control the energy to the system in a way that mimics the stretching and eventual breaking of a string. 

By preparing the system out of equilibrium and tracking its evolution over time, the researchers observed the emergence of effective charges and reconstructed the resulting string dynamics.

The team also simulated the process on a classical computer and confirmed that their experimental results were accurate. As the problem size grows in future experiments, however, only quantum computers will be able to solve these problems. 

The string-breaking process in other models was also recreated by teams led by Google and QuEra Computing on platforms built using superconducting circuits and neutral atoms, respectively, which each have their own advantages and challenges.

“These are the three platforms leading the charge in quantum computing, so it’s a nice benchmark and comparison for the quantum community,” Monroe says.

The authors say that the trapped-ion platform results mark an exciting step forward in building quantum simulations complex enough to exceed the capabilities of even the largest supercomputers, which will eventually allow researchers to explore the most fundamental questions of the universe, like matter evolution after the big bang. 

“As a physicist, it is incredibly exciting to investigate the conditions of the early universe in an atomic-level computing machine,” says Zohreh Davoudi, an associate professor of physics at UMD, who was part of the research team and is also a QuICS Fellow and a Senior Investigator at RQS. “Even the slightest insights from an out-of-equilibrium physics model will guide us in the future.”

This story was written by Andrew Tie and originally published by the Duke Pratt School of Engineering. It has been adapted here with minor changes.

This work was supported by the Department of Energy (DE-SC0020312, DE-SC0025341, DESC0019040, DE-SC0024220, DE-SC0020271), National Science Foundation (OMA-2120757), Air Force Office of Scientific Research, Defense Advanced Research Projects Agency and Amazon Web Services.

University of Maryland Associate Professor of Physics Zohreh Davoudi is one of eight academics around the globe named a 2026 Schmidt Polymath. 

Founded in 2021, the Schmidt Sciences Polymath Program recognizes risky, cross-disciplinary work undertaken by researchers who push the boundaries of their fields to achieve scientific breakthroughs. Davoudi and the other awardees will each receive up to $2.5 million over five years to support their research. 

“The flexibility and freedom offered by this award is a dream come true,” Davoudi said. “It allows one to explore the wildest ideas and not be afraid of crossing traditional boundaries set within institutions and funding agencies.” 

To date, the Polymath award has been awarded to 43 researchers at 31 institutions across nine countries.Zohreh Davoudi. Credit: Riley Sims.

“We are elated to hear of this prestigious and well-deserved acknowledgment of Dr. Davoudi’s considerable talent,” said Kara Hoffman, chair of UMD’s Department of Physics. “We are proud of her accomplishments and look forward to hearing about the many findings that this generous award will enable.”

Since joining UMD in 2017, Davoudi has worked at the intersection of nuclear physics, particle physics, and computer science. Her research explores how to build the universe from the bottom up: physicists have a good description of nature’s basic ingredients, but translating those fundamental equations into concrete predictions—about the structure of an atomic nucleus or the matter inside a neutron star—is enormously difficult. 

“Most researchers specialize in one or a few tools to close that gap,” Davoudi said. “But my approach has always been that I would pick any means that would help me solve these problems.”

Davoudi began her career as a pure theorist, working through equations with analytical methods. Her results showed how real-world quantities—the fusion reactions that power the sun and a rare nuclear decay that would prove our current theory of physics incomplete—could be extracted from numerical calculations. Then, Davoudi moved on to results obtained from supercomputers, helping to produce some of the first calculations of nuclear interactions, reactions and structure derived from first principles. But she concluded that even these large, powerful computing machines would never be enough.

“No matter how large these computers are, eventually they will come to a point where they can’t solve certain problems for us,” Davoudi said. 

That realization led her to quantum computing. Unlike classical computers, which store information as simple on/off switches, quantum computers exploit the strange rules of quantum mechanics to process certain types of problems far more efficiently. Davoudi is now considered a pioneer in the subfield that applies quantum computing to nuclear and particle physics.

When physicists try to simulate how large numbers of subatomic particles interact and evolve, the amount of information involved grows faster than any classical computer can handle. That bottleneck affects research connected to some of the world's leading facilities, including the Large Hadron Collider and the Relativistic Heavy Ion Collider, where particles are smashed together at extreme energies to reveal the fundamental nature of matter. Davoudi's work is building the tools to run those simulations on quantum computers instead.

“I develop theoretical foundations, quantum algorithms, and experimental proposals for simulating quantum systems that increasingly resemble the subatomic systems we ultimately like to simulate. This endeavor has put me in the sphere of several amazing theoretical and experimental researchers from across physics, computer sciences, and engineering at the UMD and beyond, and turned my research into an exciting multidisciplinary journey,” Davoudi said.

For Davoudi, the Polymath award will help support her next ventures into uncharted territory. She plans to bring tools she has never used before—quantum sensing and artificial intelligence—into her research, and to apply her existing expertise to fields she has not yet explored, including cosmology and even bioscience.

Davoudi sees a hidden thread connecting some of the most extreme environments in science, from the universe in its earliest moments to collisions inside particle accelerators to even the chemistry of living cells. At each scale, quantum mechanics governs the underlying physics. But at some point, those quantum effects give way to the ordinary rules of classical physics. Davoudi believes that this transition holds untapped scientific potential.

“Can we trace the ‘quantumness’ in these systems? Can we leverage it to discover new phenomena and new applications?" Davoudi said. “New simulation and sensing strategies can reach far beyond what scientists consider possible today, and artificial intelligence could accelerate that process beyond our imagination. It’s exciting to think about these directions and discover both answers and new questions in the process.”

The Polymath award will allow Davoudi to build new collaborations with scientists in quantum sensing, artificial intelligence, cosmology and beyond, and to launch new activities alongside the talent this award will support.

“I’m not an expert in any of these fields. But I am an expert in nuclear and particle physics and its intersections with quantum information science. And I am passionate about seeking answers from many different angles. That’s what I bring to the table,” Davoudi said. “I am grateful to Schmidt Sciences for placing their trust in researchers like me to explore freely in pursuit of science.”

Original story by Georgia Jiang: University of Maryland Physicist Zohreh Davoudi Named 2026 Schmidt Polymath | College of Computer, Mathematical, and Natural Sciences | University of Maryland

Distinguished University Professor James F. Drake has been selected for the John Adam Fleming Medal of the American Geophysical Union (AGU). The medal is awarded for original research and technical leadership in geomagnetism, atmospheric electricity, aeronomy, space physics, and/or related sciences. Drake was cited for pioneering theoretical investigations of space plasmas leading to discovery of fundamental properties and effects of magnetic reconnection.

James Drake

Drake received his Ph.D. from the University of California, Los Angeles, and held appointments there before joining the University of Maryland as a postdoctoral associate in 1978. He became a full professor in 1990, jointly with the Institute for Physical Sciences and Technology. At UMD, he has served as co-director of the Joint Space-Science Institute, a research partnership between the UMD Astronomy and Physics departments and NASA Goddard Space Flight Center. He was named a UMD Distinguished University Professor in 2014.  

Drake is a Fellow of the AGU and the American Physical Society, and in 2010, received the APS James Clerk Maxwell Prize for Plasma Physics for pioneering investigations of plasma instabilities in magnetically-confined, astrophysical and laser-driven plasmas; in particular, explication of the fundamental mechanism of fast reconnection of magnetic fields in plasmas; and leadership in promoting plasma science.

He has also received the Popular Writing Award of the Solar Physics Division of the American Astronomical Society.

During his career, Drake has investigated many aspects of plasma physics, including the solar corona, the earth's magnetosphere and ionosphere, magnetically confined plasma, and the interaction of intense lasers with plasma. He is now a co-Principal Investigator on the NASA Parker Solar Probe (PSP) mission, which in 2024 came within 10 solar radii of the sun. Data from the PSP will help scientists determine the mechanism that heats the solar corona and drives the solar wind. Drake is also active in the NASA Magnetospheric Multiscale Mission, which is a four-satellite effort launched in 2015 to explore the physics of magnetic reconnection at exceedingly small spatial scales.

The Fleming Medal honors geophysicist John Adam Fleming (1877–1956), who made notable contributions to the establishment of magnetic standards. It will be awarded in December at the AGU’s annual meeting in San Francisco, California.