Physics on the Field

On a Saturday in April 2023, an unusual event unfolded on the grassy greens by the University of Maryland’s Memorial Chapel. Nearly 50 students, staff and faculty gathered to play in the inaugural Physics Champions League, an amateur soccer tournament run by the UMD Physics Undergraduate Committee (PUC). Created to bring together waldych soccer 2physics majors looking for some outdoor fun, the tournament also welcomed the greater campus community, plus friends and family, to participate.

For junior physics major and PUC co-president Sarah Waldych, the idea for the tournament began last fall when she overheard classmates chatting about soccer between classes.

“I realized that a lot of us enjoyed playing soccer in our free time. Many physics majors are involved in intramural sports,” Waldych explained. “Once that clicked, it seemed so obvious to me that we had to organize a way for all of us to come together and just have fun. And it just took off from there.”

Waldych still remembers the excitement and cheering crowds from that spring afternoon. She and other PUC members ran the whole event, from facilitating team sign-ups to refereeing the games. Although many of the players were physics undergrads, graduate students, non-physics students and even a faculty member—Physics Assistant Research Professor Chandra Turpen—played on the soccer pitch that day. 

The Physics Champion League is just one of Waldych’s ideas on how to connect students outside of the classroom and build a better, stronger, tighter-knit physics community. As a member of PUC, Waldych helped organize many other programs and events for physics majors—from free hot chocolate and games during exam times to undergraduate research colloquia that help students practice their presentation skills. 

“Growing up, I realized that there wasn’t much of a science community for me to really share my experiences with. In fact, there’s sometimes a taboo about physics; it’s too hard, too intimidating, too unwelcoming, or not fun at all,” Waldych explained. “I want to help create a space where we can gather, get to know each other, share research or present anything that we find interesting, and help each other grow.” 

To reach those goals, Waldych often collaborates with Donna Hammer, the director of education programs and public engagement in physics and PUC advisor. Together, they work with students, faculty, staff and alums to ensure their needs—both research-related and recreational—are met. Hammer believes that Waldych’s work is essential to maintaining a physics community that is both vibrant and diverse. 

“Sarah’s sincere and tireless effort to make sure all physics majors feel included and their accomplishments celebrated is truly outstanding,” said Hammer. “She’s not only committed to her studies and research but also to her peers and the broader physics community.”

A journey to Germany

This summer, Waldych focused her outreach efforts on the broader physics community, spending two months in Hamburg, Germany, at the Deutsches Elektronen-Synchrotron (DESY), a national research center operating particle accelerators and conducting groundbreaking research in particle physics. Waldych worked with the Compact Muon Solenoid (CMS) experiment, a general-purpose detector at the Large Hadron Collider that can see a wide range of particles and phenomena produced in high-energy collisions.

Waldych, wearing a special gown, hairnet and gloves, is applying isopropyl alcohol to a cloth that will be used to clean all the equipment before an experiment. All the experimental work is performed in a clean room to prevent extra dust or oils from contaminating a very sensitive thermal experiment inside the vacuum chamber. Waldych, wearing a special gown, hairnet and gloves, is applying isopropyl alcohol to a cloth that will be used to clean all the equipment before an experiment. All the experimental work is performed in a clean room to prevent extra dust or oils from contaminating a very sensitive thermal experiment inside the vacuum chamber.

“I worked with the scientists at DESY and students from all sorts of backgrounds,” Waldych said. “We analyzed the systematics of a custom experimental setup designed to measure a sample’s thermal conductivity, or its ability to conduct or transfer heat. We studied the behavior of sapphire glass under multiple operating conditions and specialized criteria that aren’t usually recognized in commercial settings. Our findings will be used later to calibrate other experimental setups at DESY.” 

Waldych will bring her new knowledge and hands-on experience with particle physics back to Physics Assistant Professor Christopher Palmer’s lab, where she studies the Higgs boson, an elusive elementary particle believed to be linked to a field that gave mass to everything in the universe.  

“Sarah truly has the potential to become a great physicist,” Palmer said. “I hope that this program gave her the opportunity to see what being a particle physicist is like in the real worldbeyond the classroom.” 

Waldych hopes that she can apply the skills she learned in the lab to practice as a researcher. And she’s hopeful her experiences will also help her develop new plans to make physics more fun and welcoming when she returns to Maryland. 

“I’ll still be coming up with ways to support UMD Physics, including holding another Champions League—which we would like to run again next spring—and also promoting immersive learning experiences like the DESY program to other students like me,” Waldych said.


Written by Georgia Jiang

Brian Clark Hunts for the Most Elusive and Energetic Neutrinos

Brian Clark, a new assistant professor of physics at the University of Maryland, arrived with a mission: to detect the first ultra-high-energy neutrinos.

If spotted, these tiny, almost weightless particles that pass through matter with barely any interactions could offer a new lens through which to view the universe. The highest-energy neutrinos have about 100 times more energy than any of the particles speeding through the Large Hadron Collider, the world’s highest-energy particle smasher running underneath the France-Switzerland border. And scientists think that the energetic neutrinos are created by astrophysical events that might not leave any other detectable trace. 

“I think the general theme of the work I do,” Clark said, “is that anytime you have a chance to look at the universe in a new way, you tend to learn something. So, I'm pro finding new ways to look at the universe.”

Brian Clark

Clark brings to UMD a wealth of experience, a reputation of excellence in mentoring students and a history of leadership within scientific collaborations. His passion for looking at the universe in novel ways and for community building dates back to his undergraduate years studying physics at Washington University in St. Louis. 

During his freshman and sophomore years, Clark had a few false starts. He wasn’t a fan of quantum mechanics for its reliance on mathematical tricks and worked in a couple of condensed matter physics labs that left him unexcited. Then, he stumbled into the astrophysics research group of Physics Professor Henric Krawczynski, who was working on detecting the polarization of celestial X-rays—Clark’s first exposure to a new way of looking at the universe. 

“What really caught me with that project was how well astrophysics as a concept integrated the physics,” Clark recalled. “It doesn't utilize just one branch of physics—you have to think really cross-disciplinarily. You need to know statistical mechanics and electromagnetism and a little bit of dynamics to put all of these stories together. And I enjoyed thinking broadly in that sense.” 

In Krawczynski’s group, Clark contributed to the development of a new method for analyzing data from a type of telescope that didn’t yet exist. This type of telescope, known as an X-ray polarimeter, would look at the polarization—or orientation—of X-ray light. While X-rays coming from remote reaches of the universe have been detected before, pinning down their polarization had always been difficult. Nevertheless, polarization was expected to carry extra information about the source of the X-rays, potentially elucidating things like the way matter collapsed into a black hole. Recently, an X-ray polarimeter called IXPE launched into orbit, and the work Clark contributed to has emerged as the main data analysis method for scientists using the telescope. 

“It's been fun to watch the citation count tick up,” Clark said. 

In his undergraduate years, Clark also participated in many community-oriented activities. He was a residential advisor at his dorm and volunteered as both an orientation leader and a tour guide. During his senior year, Clark was torn between his passion for physics and his enthusiasm for community building. He applied to physics and higher education administration graduate programs. However, he couldn’t imagine leaving science altogether. By the end of his senior year, he firmly settled on physics. 

Clark enrolled at Ohio State University and joined the group of Physics Professor Amy Connolly to work on what would become the subject of his career—high-energy neutrinos. 

“He walked in my office looking for a spot and he was just glowing with enthusiasm, like he always is,” Connolly recalled. 

With Connolly’s support, Clark landed a National Science Foundation Graduate Research Fellowship to support his studies. 

“Neutrinos are really young as a discipline, especially high-energy neutrinos,” he said. “They're a pretty new way of looking at the night sky. And that was really intriguing to me. It’s a really nascent field that's just finding its feet.”

Neutrinos are a peculiar type of particle. Of all the particles that have mass, they are the lightest. They have no electrical charge and only interact weakly via gravity and the nuclear forces responsible for radioactivity. Because of this, they largely pass through matter, including humans, unimpeded, which has earned them immortality in a poem by John Updike. It’s estimated that 100 trillion neutrinos pass through you every second.

The reluctance of neutrinos to interact with anything else meant that they remained undetected until 1956. But once they were discovered, it didn’t take long for scientists to conceive of using neutrinos as a sort of telescope to look at the universe. Scientists first spotted neutrinos coming from the sun in 1968, but it took until 2013 for anyone to find neutrinos originating from outside the solar system. These were detected by an experiment called IceCube, located at the South Pole in Antarctica. 

The basic idea of the IceCube experiment is simple: Neutrinos almost never interact, but one way to catch them is to provide a really big target and wait around for signs that a neutrino smashed into it. Luckily, the big target already exists—ice around the South Pole is dense enough to provide a decent chance of interaction, and there’s lots of it.  So, scientists buried detectors deep into Antarctic ice sheets. If, by chance, a neutrino comes close enough to one of the atomic nuclei inside the ice molecules, it will cause something akin to an explosion, sending out a shower of particles and radiation, from flashes of optical light to radio waves. 

The IceCube detectors capture the light, which indicates what direction a neutrino came from and how much energy it had. This provides a new way to look at the universe, distinct from optical imaging with tools like the James Webb Space Telescope or gamma and X-ray detectors. Neutrinos carry information about powerful cosmic events, like exploding stars and black holes, that are hard to see by other means. 

IceCube’s method for detecting astronomical neutrinos works well for neutrinos that carry up to about a trillion times the energy of a typical electron meandering around a hydrogen atom. But for the ultra-high energies that Connolly’s group was interested in—another million times more energetic—it was destined to fall short. 

Ultra-high-energy neutrinos are likely produced by cosmic ray bursts that are otherwise too difficult to see because their heavier components get bent by magnetic fields and everything but neutrinos gets bogged down in the celestial sludge left over from the early universe known as the cosmic microwave background. These neutrinos are extremely rare, and the volume of ice filled with IceCube detectors is too small to stand a reasonable chance of catching one. 

To increase the volume of detection, scientists turned to radio-wave detectors. The radio signal produced by neutrino explosions in ice is stronger for the highest-energy neutrinos, and it’s also able to travel much farther through ice without getting absorbed. So, fewer radio detectors can be placed larger distances apart to capture signals from a greater volume. In hopes of catching some ultra-high-energy neutrinos, scientists started building the Askaryan Radio Array (ARA), an array of radio detectors near the IceCube experiment, to detect neutrino events anywhere within 10 cubic kilometers of ice (compared to 1 cubic kilometer for IceCube). 

As a graduate student, Clark got his hands dirty with every aspect of the ARA experiment. He built two of the five radio detectors that were deployed and refurbished two more. He then went down to Antarctica, where he played a role in installing the detectors into the ice. 

“Antarctica was a really wild place,” Clark said. “It's constantly trying to kill you. But it's also a really beautiful place with a really unique community. It was great.”

After returning from Antarctica, Clark led the most comprehensive data analysis of ARA’s high-energy neutrino search to date. So far, they haven’t caught any of the elusive particles. But for this type of detector, they set the tightest limits on how many ultra-high-energy neutrinos could be hitting Earth. They developed efficient data analysis techniques that could be applied to a variety of detectors, operating over many years. 

“The detectors always look and behave a little bit differently, but you have to rely on all of them working together in order to do the science,” Clark said. “We demonstrated that you can do this kind of analysis at scale—that you can take data from detectors that look a little bit different, behave a little different and have been running for a long time.”

In addition to his hardware contributions, Clark also helped develop software that models neutrino interactions to aid in designing the next generation of detectors. In particular, he focused on how the signal from a neutrino explosion propagates through the ice. This is no easy task—the ice changes density from bottom to top, and the model needs to simulate millions of optical or radio signals traveling through it. Clark and his collaborators found and implemented an efficient way to model the curved trajectories the signals take, enabling the simulation to run in a reasonable timeframe. 

Clark’s mastery of all aspects of the ARA experiment, as well as his approachable nature, made him a valuable resource for junior members of the project and other collaborators. 

“One thing that’s really characteristic of Brian is what a fantastic mentor he is,” Connolly said. “He's always there to help, almost to a fault. I would always tell him, ‘Brian, you can point people to other places to get information.’ But everyone always wants to talk to Brian.”

After earning his Ph.D., Clark was awarded the prestigious NSF Astronomy and Astrophysics postdoctoral fellowship. He joined the physics and astronomy department of Michigan State University and brought the high-energy neutrino program there for the first time. 

“He was largely independent,” said Tyce DeYoung, one of Clark’s co-advisers at Michigan State and an associate professor of physics and astronomy. “He was sort of breaking new ground for the group here at Michigan State.

While there, Clark extended the search for ultra-high energy neutrinos to optical signals by finding new ways of analyzing data from IceCube. He also played key roles in planning the next generation of IceCube and a new neutrino-detection experiment being built in Greenland called the Radio Neutrino Observatory in Greenland (RNO-G), which has become part of his research focus at UMD. 

Throughout his graduate and postdoctoral career, Clark carried on his passion for community leadership and mentorship. As a graduate student, he helped design and facilitate Ohio State’s ASPIRE program, a hands-on physics research workshop for high school girls. He also brought physics demos to elementary schools and served for 18 months on his department’s Climate and Diversity Committee. As a postdoc, he was an early career scientist representative to the IceCube governance board and served on the IceCube collaboration’s working group on diversity and inclusion.

DeYoung appreciated Clark’s involvement with community building. 

“It was a great pleasure to work with him and to see him broaden his horizons while he was here, and to start to think about not just the scientific aspects of how you build a detector and how you analyze data, but also expanding to thinking about how you organize people to build these big projects and to operate these big projects,” DeYoung said. “How do you communicate with the scientific community and foster the sort of scientific community that we want?”

Now, Clark is looking forward to bringing his passions for the high-energy neutrino search and community building to UMD. 

“UMD is a really exciting nexus,” Clark said. “It's a really unique blend of experimental approaches, that makes it a unique place.”


Written by Dina Genkina

Advocating for Quantum Simulation of Extreme Physics

The Big Bang, supernovae, collisions of nuclei at breakneck speeds—our universe is filled with extreme phenomena, both natural and human-made. But the surprising thing is that all of these seemingly distinct processes are governed by the same underlying physics: a combination of quantum mechanics and Einstein’s theory of special relativity known as quantum field theory.

Theoretical nuclear and particle physicists wield quantum field theory in their efforts to understand interactions between many particles or the behavior of particles with extremely large energies. This is no easy feat: At least theoretically, quantum field theory plays out in an infinite universe with particles constantly popping in and out of existence. Even the world’s biggest supercomputer would never be able to model it exactly. Fortunately, there are many computational tricks that can make the problem more tractable—like cutting up the infinite universe into a finite grid and taking judicious statistical samples instead of tracking every parameter of every particle—but they can only help so much. 

Over the past few years, a growing group of scientists has become wise to the potential of quantum computers to approach these calculations in a completely new way. With a fully functioning quantum computer, a lot of the approximations could be avoided, and the quantum nature of the universe could be modeled with true quantum hardware. However, quantum computers are not yet big and reliable enough to really tackle these problems, and the algorithms nuclear and particle physicists would need to run on them are not yet fully developed.

“Even if we have large-scale, fully capable quantum computers tomorrow,” said Zohreh Davoudi, associate professor of physics at UMD, “we don’t actually have all the theoretical tools and techniques to use them to solve our grand-challenge problems.”Zohreh Davoudi

Classical computers require exponential resources to simulate quantum physics. To simulate one extra tick of the clock or include one extra particle, the amount of computing power must grow significantly. So, the classical methods resort to approximations that fall short because they leave out details and lose the ability to address certain kinds of questions. For one, they can’t keep up with the real-time quantum evolution of the early universe. Additionally, they can’t track what happens during collisions of heavy nuclei. And finally, they are forced to ignore the quantum interactions between the myriad particles in high-energy settings, like those that are emitted from an exploding star. A quantum computer, however, could tackle these problems on their own quantum turf, without needing as many resources or resorting to as many approximations.

Now, researchers want to make sure the nascent effort to use quantum computers to simulate the extreme events of the universe continues to thrive. Davoudi, along with JQI Adjunct Fellow and College Park Professor of Physics Chris Monroe and other researchers, penned a whitepaper laying out the case for funding quantum simulation research in particle physics, published in the journal PRX Quantum in May 2023. Davoudi also co-authored a similar whitepaper in the field of nuclear physics, available on the arXiv preprint server.  

“It's a responsibility of researchers to also think at a larger scale,” said Davoudi, who is also a Fellow of the Joint Center for Quantum Information and Computer Science (QuICS) and the associate director of education at the National Science Foundation Quantum Leap Challenge Institute for Robust Quantum Simulation (RQS). “If we think this field is intellectually promising, interesting, and worth investing in as a scientist, we have to make sure that it stays healthy and lively for generations to come.”

Some sub-fields of physics, including the nuclear and particle physics communities, engage in long-term planning for the future of their field. Nuclear physicists in the U.S. plan seven years ahead, and particle physicists plan a full decade ahead. Researchers from many universities and national laboratories come together in meetings, seminars, and panel discussions over the course of a year to decide what the highest priorities in the field should be. Funding agencies in the U.S. and worldwide have historically taken these conclusions seriously. The whitepapers developed by Davoudi and her co-authors are a part of those efforts. In them, they argue for the importance of studying quantum simulation for nuclear and particle physics and make specific recommendations for further development. 

“These new research directions in both nuclear physics and high-energy physics were not part of the last U.S. long-range planning processes, because the idea had simply not been introduced at the time,” Davoudi said.

Indeed, the ideas weren’t even on Davoudi’s radar six years ago when she came to UMD to join the physics faculty as a theoretical nuclear physicist. While she was busy searching for an apartment, Davoudi saw an announcement for a workshop hosted by QuICS exploring the intersection of her field with quantum computing. Instead of looking for a place to live, she spent several days at the workshop, talking to theorists and experimentalists alike. 

Davoudi was enticed by the promise of quantum simulations to solve the kinds of problems she was unable to address with classical computational tools, and it changed the course of her career. In the years since, she has developed new theoretical techniques and collaborated with experimentalists to push the boundaries of what quantum simulators can do to help uncover the basic physics of the universe.

Davoudi wants to ensure that this burgeoning field continues to thrive into the future. In the whitepapers, she and her co-authors identified specific problems where quantum computing holds the most promise. Then, they made three main recommendations to ensure the success of the field for the next seven to 10 years. 

First, they recommended funding for theoretical efforts to develop algorithms that run on quantum hardware. Even though the potential of quantum computing is clear, detailed algorithms for simulating quantum field theory on a quantum computer are still in their infancy. Developing these will require a dedicated effort by the nuclear and particle physics communities. 

Second, they advocated for greater interdisciplinary communication between the nuclear, particle and quantum physics communities. Different quantum computer architectures will have different quirks and advantages, and the field theory folks will need to have access to them to figure out how to make the best use of each one. Certain implementations may, in turn, become motivated to engineer specific capabilities for the kinds of problems nuclear and particle physicists want to study. This can only be accomplished through close interdisciplinary collaboration, the authors claim. 

“As a community, we cannot isolate ourselves from the quantum information and quantum technology communities,” Davoudi said.

Third, Davoudi and her co-authors believe it is key to bring in junior researchers, train them with a diverse set of skills, and give them opportunities to contribute to this growing effort. As with the QuICS workshop that inspired Davoudi, the community should invest in education and training for the relevant skills through partnerships between universities, national labs and the private sector. 

“This is a new field, and you have to build the workforce,” Davoudi said. “I think it's important for our field to bring in diverse talent that would allow the field to continue to intellectually grow, and be able to solve the problems that we would like to eventually solve.”


Written by Dina Genkina

Sasha Philippov Investigates Plasma Around Black Holes and Neutron Stars

Curiosity about the cosmos has attracted many young astrophysicists to their careers, but that was not the case for Alexander “Sasha” Philippov. While growing up in Russia, he was a natural at science and even competed in the national Physics Olympiad for high school students. However, his interests at the time were more down-to-earth.Sasha PhilippovSasha Philippov

“I was not into astrophysics whatsoever,” said Philippov, who joined the University of Maryland’s Department of Physics as an assistant professor in May 2022. “When I went to college, I was hoping to do theoretical particle physics, but my advisor and mentor, Professor Vasily Beskin, showed me that you can do very interesting, detailed modeling in astrophysics. It looked like real physics to me—not just looking into a telescope and watching the stars.”
Philippov has been starstruck ever since, using a combination of theory and computer modeling to tackle big questions in high-energy astrophysics and publish over 60 papers. 

After completing his undergraduate studies at the Moscow Institute of Physics and Technology, he earned a Ph.D. in astrophysical sciences from Princeton University in 2017. It was during his graduate studies that he started specializing in the physics of plasmas—a state of matter comprising hot, ionized gas that surrounds “some of the most mysterious and exotic objects in the universe,” including black holes and neutron stars, Philippov said. 

He was then named a NASA Einstein and Theoretical Astrophysics Center Fellow and completed his postdoc at UC Berkeley, where he co-developed computer code to model the behavior of charged particles around rotating black holes.

“This sort of thing had never been modeled before, because you need to take into account the effects of general relativity, how the electromagnetic fields are modified by the spinning black hole and how they react to the dynamics of charged particles,” Philippov explained. “Ours was the first code that could do it.” 

His code enabled a flurry of studies—including five publications in the journal Physical Review Letters—which offered new insights into the extraction of energy from rotating black holes, the production of electron-positron plasmas and electromagnetic flares near the event horizons of black holes, and the accretion of collisionless plasma.

After his postdoc, Philippov worked as an associate research scientist at the Simons Foundation’s Flatiron Institute in New York City, where he continued to study the emission mechanisms of pulsars—magnetized neutron stars that rapidly rotate. During this time, he constructed the first models capable of explaining the mysterious coherent emission of pulsars, which were found to produce relativistic lightning strong enough to shoot beams of radio waves out into space. Although this cosmic phenomenon was discovered more than 50 years ago, its cause was not fully understood until Philippov’s study.

Recently, he was named deputy director of a multi-institutional Simons Foundation project called the Simons Collaboration on Extreme Electrodynamics of Compact Sources (SCEECS). The team will model electrodynamic processes related to neutron stars and black holes, which have magnetic fields that are 10 billion times stronger than those associated with the Large Hadron Collider in Switzerland.

The group will use kinetic plasma simulations and large-scale fluid-type modeling to study the underlying emission mechanisms of magnetars—neutron stars with the strongest magnetic fields—and spinning black holes. Advances in high-performance computing and telescope technologies help make this work possible.

“It’s a big investment for research that is completely theoretical,” Philippov said of the grant. “We will be looking at a collection of both completely new and very old problems—the latter having been revitalized by the power of computer simulations and new observations. It’s a great time to do this.”

Philippov also recently received a $600,000 grant from the National Science Foundation to support the modeling of phenomena in extreme plasmas around black holes and neutron stars. In addition, he continues to study the radiation of neutron stars (including enigmatic fast radio bursts), flares from accreting supermassive black holes and merging neutron stars, and particle acceleration in jets produced by black holes. 

As a Fellow in the Joint Space-Science Institute (JSI), a collaboration between the NASA’s Goddard Space Flight Center and UMD’s astronomy and physics departments, Philippov is helping to organize a workshop in October 2023 that will share the latest expertise on “winds throughout the universe,” including everything from the sun’s powerful wind to the gusts produced by merging neutron stars.

In his day-to-day work, Philippov works closely with students and postdoctoral fellows and said he “tremendously enjoys mentoring and interacting with early career researchers.” 

Though he was not instantly smitten with astrophysics as a high school student, he is happy he pursued this career path. For him, having the chance to ponder big questions in astrophysics—and better yet, to answer them—is what continues to drive his research.

“The time that you get to study something completely new is why we are in this business,” Philippov said. “The joy of getting to finally understand something after a long time is remarkable.”


Written by Emily Nunez.