Aaron Sternbach Combines Light and Matter to Push Experimental Boundaries

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Published: Monday, February 26 2024 09:24

Aaron Sternbach, a new assistant professor in the Department of Physics at the University of Maryland, is an expert in combining light and material properties to produce unique results. His experiments have allowed him to spy on elusive quantum interactions that play out on extremely small and fast scales.

“I study quantum materials with light,” Sternbach said. “When I encounter something I can’t see with light because of common ‘limits,’ I study the physics behind these limits and try to push them further. That is a really fun part of the job. In some cases, that approach can lead to new opportunities.” 

Since he was a kid, Sternbach enjoyed math and physics. But even as he enrolled to study physics as an undergraduate at Boston University, he wasn’t certain that he wanted to pursue a career in physics. During his freshman and sophomore years, he worked in an astrophysics lab where he spent most of his time helping design measurement devices. But after almost two years of work, his efforts hadn’t produced a physical device. The project wasn’t progressing at a pace he found satisfying, so he considered switching majors to study medicine in his junior year. Aaron Sternbach

That changed after he spent his summer working in physicist Richard Averitt’s lab. He assisted with an experiment that used light to manipulate the electrical properties of a quantum material. In the project, light drove the material from being a poorly conducting insulator to an electrical conductor. Achieving the transition required focusing the light into a smaller spot than is possible using lenses or other common techniques. Instead, it required taking advantage of the material’s structure. 

A material’s response to light is dictated by its internal structure, and the project was looking at just one of the countless possible materials that scientists can find in nature or deliberately engineer. Sternbach became hooked on physics when he started to explore simulations of materials as part of the project, and he never looked back.

"I found it fascinating that engineering light could totally change the properties of a quantum material," Sternbach said. "I started playing with all sorts of simulations to try to understand how far this approach could go."

He started to wish he could watch the transitions between insulator and conductor in experiments as they played out in real space and real time. In 2013, that desire led him to graduate school at UC San Diego, where he joined the lab of Dimitri Basov. Basov had recently been investigating new techniques that used material properties to focus light into unusually small spots. His early results showed that the approach could be useful for observing and learning about quantum materials. In the middle of his graduate studies, Sternbach moved to Columbia University when Basov relocated his lab there.

Working with Basov, Sternbach helped develop a new observation technique that can observe very quick changes while also getting around a rule in physics called the diffraction limit. The diffraction limit is the inevitable result of the way that waves, including light, spread—diffract—when they pass the edge of an object and then keep spreading as they travel. For devices that use lenses and apertures to manipulate light, the diffraction limit imposes strict constraints both on the smallest spot a beam of light can be focused into and on the smallest features that the device can be used to clearly distinguish. However, by using the structure of a material to continually influence light, researchers can circumvent the diffraction limit and build new tools for manipulating and observing the microscopic world. 

The observation technique that Sternbach helped develop simultaneously uses the material’s structure to herd light along paths that beat the diffraction limit and uses very short flashes of light to accurately capture quickly unfolding events as they play out over time. To get clear snapshots of rapidly changing experiments, the team used extremely short flashes of light, providing a clear view of brief periods instead of capturing a blurry image like an overexposed photograph. 

“Learning to interact with data and gaining an intuition for what you're seeing is like learning a new language,” Sternbach said. “You learn fantastic approaches to see parts of the world that are way beyond a native human scale.”During positive refraction (green) the path of incoming light (blue) will bend, but it will never cross the dotted line perpendicular to the interface of the two materials. In rarer circumstances, called negative refraction (red), the light sharply turns and continues on the same side of the dotted line. (Credit: Bailey Bedford, UMD)

As part of his graduate work, Sternbach got to apply the technique he’d developed to observe materials transforming in real space and in real time after light was used to initiate a change.

After completing his degree, he continued to work with Basov as a postdoctoral researcher. In a new project, they incorporated an additional way that light and matter can interact. They studied polaritons—particle-like combinations of light and matter with characteristics of both. Since the matter portion of a polariton contributes mass, polaritons behave more like matter than normal light: They can carry significantly more momentum than light and can be more tightly confined into a beam than freely propagating light. 

Sternbach and his colleagues wanted to observe a particular type of polariton, called a hyperbolic polariton, that travels through the bulk of a material along a specific type of constrained path. In an article published in the journal Science in 2021, the team shared how they created polaritons by hitting a layered material with a pulse of light and then used their new technique to observe polaritons and follow their journey through the material. Their measurements revealed details about quantum states that were crucial to the polaritons’ existence and that only existed in the material for trillionths of a second. 

Following that experiment, Sternbach and his colleagues studied hyperbolic polaritons that moved between two different adjacent materials. They investigated two naturally occurring materials that were known to produce polaritons and revealed that a polariton’s path would bend in an unusual way as it passed across the interface between the two materials. 

Normally when light travels between two materials, such as water and air, its path bends slightly based on the fact that it travels at different speeds in each material. This bending of light—called refraction—is why a straight straw placed in a glass of water looks like it bends at the interface. 

In an article published in the journal Science in 2023, Sternbach and his colleagues showed that when they properly oriented the two materials, the polaritons at the interface didn’t refract normally. 

Most materials produce positive refraction, where light is deflected a bit but is limited in how far it can swerve to either side. Positive refraction is similar to a simple dive into a swimming pool: The diver’s direction will change some when they move into the water, but as they continue down, they also keep moving forward. 

Sternbach and his colleagues observed their polaritons bending in a more drastic way, called negative refraction. During negative refraction, a beam almost does a U-turn. While it continues down into the new material, it also travels backwards, like a diver who instantly makes a sharp turn as they hit the water so that they end up under the diving board instead of in front of it. 

The team’s experiment revealed that producing negative refraction in the experiment depended on getting the top layer turned at just the right orientation to the bottom layer. The team went on to use negative refraction to create a tiny container for trapping light. They demonstrated that when the polaritons were reflected at the exposed surfaces of each material, the negative index of refraction allowed the polaritons to become stuck in a loop that is much smaller than the wavelength of the light outside the materials. 

Now that Sternbach has joined UMD, he plans to continue this line of research in his own lab, where he hopes to create a supportive environment for students. He is currently looking for new students to join him in exploring quantum materials and the complex interactions that can be engineered between light and matter. 

“I always felt that exploring curiosities and doing things that I really enjoyed doing was enough,” Sternbach said. “And I think that was a good rule of thumb. It's allowed me to explore this direction, which is basic research, freely and grow in whatever direction nature allows. I'm very excited to see where this goes in the future at Maryland.”

Story by Bailey Bedford

The Sternbach group is always looking for exceptional graduate and undergraduate students as well as postdoctoral researchers who wish to join the team. Those interested may reach out to him by email at This email address is being protected from spambots. You need JavaScript enabled to view it..

Kasra Sardashti Brings Summer Program to UMD to Promote Diversity in Quantum Research

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Published: Monday, February 26 2024 09:24

Quantum research involves many challenges, from building tiny intricate devices and interpreting the unintuitive microscopic world to grappling with unwieldy calculations. The community of quantum researchers also has to contend with societal issues, like the long-established racial and gender disparities in physics and trends that overhype or mystify quantum technologies. 

As a quantum researcher, Kasra Sardashti, who joined the UMD Department of Physics in March as an assistant research professor and a principal investigator at the Laboratory for Physical Sciences (LPS), takes a practical, hands-on approach to problem solving. His research focuses on removing bottlenecks that limit the development of practical quantum devices. He’s also tackling another problem he believes is holding back quantum research: a lack of diversity in the researchers joining the field.

“I have a strong commitment to promoting diversity in STEM,” Sardashti said. “I've always found it surprising that there is such a significant underrepresentation of women and minorities in physics and engineering.”

According to data through 2021 from the American Physics Society, the American Institute of Physics and the Integrated Postsecondary Education Data System, women received fewer than 22% of physics doctoral degrees annually in the U.S. And the five-year average of data through 2021 shows that while communities marginalized by race or ethnicity made up about 37% of the U.S. college-age population, members of those communities earned only 15% of the physics bachelor’s degrees and 8% of the doctoral degrees and held only 5% of physics faculty position.

Sardashti has seen colleagues from diverse backgrounds bring valuable new ideas and perspectives to the quantum research community—a field that is steadily growing. He wants to ensure it has a robust, diverse workforce to support its growing needs, and he doesn’t believe that getting more people into physics or math classes will be sufficient to get enough people working in the field. Getting people interested in quantum research often requires getting them past a discomfort with quantum physics, which Sardashti calls “quantumphobia.” 

Sardashti believes the most effective way to counter quantumphobia is letting students perform experiments themselves so they can see the practical side of the field and have fun getting their hands on real projects. He decided to apply that approach in his efforts to attract students from underrepresented groups into the field. Last year, he and his colleagues started the Summer Quantum Engineering Internship Program (SQEIP) to give diverse groups of undergraduate students the chance to get their hands on equipment in real quantum research labs and gain practical experience with quantum engineering.

When Sardashti moved to UMD, SQEIP came with him. The facilities and researchers at the LPS Qubit Collaboratory and UMD’s Quantum Materials Center (QMC) created a new home for the program, and this summer they introduced 15 students to quantum research. 

“I think that the part that drew me to science and engineering was actually doing things with my hands and getting a hands-on experience—experiential learning,” Sardashti said. “I think we should provide that to students. And this is how we jump started the program.”

Sardashti’s own path to quantum physics started from a practical, hands-on background. As a kid, he enjoyed working on things, like fixing computers and working on the wiring in the walls of his family’s home in Tehran.

Pursuing his practical interest, he attended Tehran Polytechnic where he studied materials engineering. Physics classes were required for the major, and the quantum physics ideas from the classes ensnared his imagination. So, he added extra physics courses to his schedule. 

He continued studying materials science while pursuing his master’s degree at the University of Erlangen in Germany and his doctoral degree at the University of California, San Diego. During this time, his interest in physics attracted him to the intersection of material engineering and applied physics, and he studied the materials that make solar panels function. After that, he dove into quantum research as a postdoctoral researcher at the New York University Center for Quantum Phenomena and then as an assistant physics professor at Clemson University.

Now, Sardashti specializes in improving quantum devices and enabling new uses for the technology. His work includes studying how superconductor fabrication processes affect the resulting properties, designing voltage-tunable superconducting quantum devices, and proposing experiments to demonstrate non-Abelian statistics using quantum devices. 

As Sardashti carried out his research, he kept noticing a lack of diversity around him and began searching for a way to address the issue. He decided he needed help to reach students who are underserved by the current system, so he began contacting professors at historically Black colleges and universities (HBCUs) looking for someone interested in working with him. After several dead ends, John Yi, a chemistry professor at Winston-Salem State University (WSSU) responded, and they started collaborating. 

“A lot of it was John's drive,” Sardashti said. “It's not that easy to go into an HBCU, pull a professor away from their four-course semester schedule, and be like, ‘Hey, can you just do something on the side?’ But he was willing to do it. He really wanted to get engaged. He's really passionate about training his students.”

Together Sardashti and Yi obtained funding from the National Science Foundation and the U.S. Department of Energy and launched SQEIP to give students, particularly those from underrepresented backgrounds, firsthand quantum engineering experience. The program gathered its first group of 11 students at Clemson University in summer 2023.

Yi is instrumental in running the program and takes a lead role in recruiting and selecting students from underrepresented backgrounds from both his own university and across the country. 

SQEIP hit a road bump when Sardashti joined UMD in March, just a couple of months before the program’s second summer. Even though it was a tight schedule, Sardashti and Yi decided to relocate the program and take advantage of the experts and labs at UMD. In just a couple of months, they had to get local scientists and faculty to buy into the effort and agree to share their time, expertise and resources with visiting students. They also had to arrange student financial support, travel and housing. Fortunately, they connected with UMD Physics Professor and QMC Director Johnpierre Paglione, who helped run the program, recruit other colleagues and arrange for the students to work in QMC labs. 

“After learning about SQEIP, I was delighted to participate by incorporating quantum materials training into the program,” Paglione said. “This was quite natural for us, since we run a condensed version each year as part of our Fundamentals of Quantum Materials Winter School, and QMC has the facilities to accommodate such a group.”

This year SQEIP included five students from WSSU and 10 students from nine other universities. Once the students arrived at UMD in May, they were split into two groups, which each spent three weeks at either QMC or LPS before swapping for another three weeks. 

At QMC, the students explored how materials used in quantum devices are created and studied. For example, they used ultra-high-temperature furnaces and arc melting station (which can reach temperatures up to about 2,000 F and 3,600 F, respectively) to make their own crystal materials by carefully combining chemicals they had measured and mixed together. They were also trained to use techniques, like X-ray diffraction and X-ray fluorescence, to observe the structures of materials they had fabricated. They also measured the physical and magnetic properties of materials in very high magnetic fields and ultra-low temperatures.

“It’s really amazing to see students come into QMC without any experience and learn to synthesize novel materials like topological insulators and superconductors, all in a matter of a few weeks!” Paglione said. “Growing crystals is one of those things that’s fun and exciting, while also crucial to helping nurture a deep appreciation for the materials that will form the next generation of quantum devices.”

At LPS the students tackled several projects that introduced them to the basics of quantum device research. For instance, they dipped electric circuits into liquid nitrogen (which is below −321 F) to observe how the electrical conductivity changed with temperature. They then explored even colder temperatures using laboratory equipment, like a dilution refrigerator, which can produce temperatures less than a tenth of a degree above absolute zero. Extremely cold temperatures are often essential to getting quantum devices to function, and the students used the frigid conditions when measuring the properties of superconductors and microwave cavities, which play crucial roles in many quantum devices. 

“I think the most beneficial part of the program is just the ability to utilize the resources that QMC and LPS had that you probably wouldn't get at your run-of-the-mill university,” said Taylor Williams, an information technology major at WSSU who participated in the program this year. “Working hands-on with the dilution refrigerator—that surprised me, just because it's so expensive. So, I was thinking we would tour it and look around, but I didn't think we'd actually get to play with it and analyze data off of it.”

By exposing the students to quantum engineering techniques, the program not only lets them connect with the field of quantum research but also provides them with context on how jobs in other fields might interact with or support quantum engineering. For instance, if participants end up going into chemistry and are producing new materials, their experiences during the program will provide insights into how those materials might be used in quantum devices. 

“It's a great learning experience and a great way to start off with a lot of different options and different directions for where you want to go,” said Brenan Palazzolo, a physics major from Clemson University who participated in the program this year. “Any STEM major should apply. It was really an amazing program to have such a broad spectrum of students.”

The program wasn’t all work. Projects weren’t scheduled on the weekends, so participants had a chance to explore the area and see tourist sites like the White House, Smithsonian museums and the Lincoln Memorial in nearby Washington, D.C. Students also found time to have fun in the labs, like a group that used a microscope to get an up-close look at colorful flecks in rocks they had bought at a Smithsonian gift shop. 

“I liked that we were really close to D.C.,” Palazzolo said. “It was kind of fun on the weekends and also really informative during the week. It wasn't just one thing that I was learning. I was learning the ins and outs of a lot of different parts of quantum research and the quantum processes for materials.”

Even after students return home, the program continues to provide advice to the participants and support their career progress. Alumni can request financial support to attend academic conferences where they can practice communicating about research, connect with scientists from other institutions, and get a sense of the broader opportunities available in the field. Alumni are also invited to apply for the following year’s program so that they can tackle more advanced projects using the techniques they learned the previous year.

“Johnpierre, myself, our leadership team at LPS, we actually believe in this,” Sardashti said. “I think this is a very good step—an important step—for people to get drawn to the field.”

Story by Bailey Bedford

Exploring the Mechanics of Life’s Tiniest Machines

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Published: Monday, February 26 2024 09:24

Maria Mukhina hopes to shine a new light on how the intricate machinery of life works at its most fundamental level. 

With a background in physics, optics and nanotechnology, the assistant professor of physics who joined the University of Maryland in January 2024 studies how cells use mechanical energy to organize themselves and carry out their jobs—both when they’re healthy and when they’re not. Mukhina develops nanoscale tools to visualize and quantify the mechanical forces within cell nuclei. Her work focuses on the mechanical information processing in DNA and chromosomes, which could lead to a better understanding of gene expression, disease mechanisms and how complex structures like tissues form. Maria Mukhina

“Physics is just as important for controlling cell physiology as chemicals and genes,” Mukhina explained. “Yet, we know very little about the mechanics that emerge when millions of molecules come together in larger dynamic structures like the genome or cytoskeleton. This is due to the lack of appropriate tools that would allow us to read out the properties of these mechanics—and that is where my work comes in.”

Physics Chair Steven Rolston said Mukhina’s research will provide UMD students with new perspectives on how physics can be applied to many other disciplines, from biology to materials science. 

“Dr. Mukhina’s training in the optical physics of nanocrystals gives her unique insights in applying techniques based in physics to study genome mechanobiology—the interplay of mechanical forces with biological function,” Rolston said. “We are delighted to have her join our biological physics effort in the department.”

Using tiny tools to solve big mysteries

Growing up in Russia, Mukhina had no idea she would eventually pursue an academic career in physics. Raised in a family of musicians, engineers and doctors, she had no lab or research experience until she entered ITMO University in St. Petersburg as an undergraduate studying laser physics. 

“I was in third year of my undergraduate education when I finally realized that I could be working in a research lab looking for answers to a real scientific question,” she recalled. “Ever since then, I’ve been in love with experimental work in the lab. Nothing can compare with sitting there in the dark, doing some microscopy work and knowing something that no one else under the sun knows—it’s like pure magic!”

Mukhina brought that sense of wonder to her graduate studies at ITMO University, earning a master’s degree in photonics and optical computer science and a Ph.D. in optics. Her doctoral research focused on the new optical properties arising in spatially ordered ensembles of anisotropic nanocrystals, tiny semiconductor particles with unique properties that can be controlled by changing the size and shape of a nanocrystal. 

After that, Mukhina wanted to explore more biological applications for this rapidly evolving technology, so she joined the lab of Harvard University cell biologist Nancy Kleckner as a postdoc.

“The Kleckner lab introduced me to the world of cellular mechanics,” Mukhina said. “We viewed chromosomes as mechanical objects rather than carriers of genetic information. This perspective led me to a whole new world of questions about how physical forces can shape the behavior of cells. I was fascinated by the idea that one can use nanotools to do work in a living cell, to change how it performs its functions, and also how this branch of research draws so heavily from physics, cell biology, chemistry and more.”

The interdisciplinary nature of that work led Mukhina to look for research environments that could provide a space for both collaborative research and innovative thinking. She found the perfect new home for her research at UMD.   

“I wanted to find a place where I could interact with very diverse faculty and resources,” Mukhina said. “And beyond the university, I am also close to many cutting-edge research hubs like the U.S. National Science Foundation and the National Institutes of Health. I’m very excited to join a group with such varied expertise.”

Now, Mukhina’s biggest research challenge is to accurately measure nanoscopic forces without disrupting the delicate environment of living cells. Drawing on her background in physics and nanotechnology, she develops tiny probes that can be directly introduced into cells to map out the forces at work within them. 

One probe is based on a concept called “DNA origami”—a technique that uses complementarity of two DNA strands to fold them into specific shapes. Another probe relies on a phenomenon called mechanoluminescence, where mechanical stresses applied to a material cause it to emit light. Both tools are designed to respond to the minute mechanical forces generated by mammalian cells, allowing researchers to create very detailed 4D maps of the intracellular force fields, which, as the researchers hypothesize, are used by the cells to orchestrate changes across microns of space, a huge distance in the cell universe. 

“All of this requires very fast and gentle to the cells light microscopy, so I’m also currently building a custom microscopy setup that will allow me to measure fluorescence or mechanoluminescence in events that occur within milliseconds,” Mukhina said. 

Mukhina also sees potential long-term applications for her research in medicine and beyond.

“Understanding the mechanics of how cells divide and segregate DNA could provide insights into cancer development or help us learn how to restart regeneration of our heart muscle cells after birth,” she explained. “My goal is for my work to open new avenues into developing regenerative therapies—and to push the boundaries of what we know about these physical forces that shape life itself.”

High School Student Earns Accolades for Summer Research with Gorshkov Group

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Published: Monday, February 26 2024 09:24

Jason Youm, a high school student who performed summer research with Alexey Gorshkov, an adjunct associate professor of physics at UMD, in 2023, placed in the top dozen competitors in the physics and astronomy category at the Regeneron International Science and Engineering Fair (ISEF). In the competition, Youm, who recently completed his junior year at Montgomery Blair High School in Silver Spring, Maryland, presented research he completed under the mentorship of Gorshkov and Joseph Iosue, a graduate student in physics at UMD.

The Regeneron ISEF brings together high school students from across the world who earn their spots by qualifying at local science fairs. In his project, Youm performed calculations to help researchers investigate how quantum computers can perform certain tasks significantly faster than their traditional counterparts.

“I'm truly, really thankful for the research opportunity,” Youm said. “I think it's honestly changed my life. It's truly an invaluable experience.”Jason Youm

Youm had harbored an interest in quantum physics for the first couple of years of high school, and after finishing his first calculus class during his sophomore year, he decided to look for opportunities to explore the interest more deeply. 

“Kind of on a whim, in mid-May, I just emailed some professors at UMD, because I heard they had a good program in quantum physics,” Youm said. “I just asked like, ‘I'm interested in these fields. Would you be interested in having a student intern during the summer?’ And Alexey was kind enough to accept me into the group.”

Gorshkov first looked over the relevant experience in math and physics Youm shared in his email and then reached out to the other members of the group to ask if any of them had a suitable project.

One of those graduate students, Iosue, was particularly interested in mentoring someone since he knew firsthand how valuable such experiences can be. When he was an undergraduate at the Massachusetts Institute of Technology (MIT), he had spent a summer working in Gorshkov’s group.

“My time as an undergrad in Alexey’s group was a very good experience for me,” Iosue said. “It was the best research experience I had until I started my Ph.D. So, I wanted to do something similar for someone else.”

Iosue remembered a project from his early days as a graduate student that had a natural continuation. The group hadn’t followed up on the possibility yet, and he thought the remaining work might be a suitable project for a motivated high school student.

The project developed mathematical tools for studying quantum entanglement—a phenomenon where the evolving fates of quantum particles become inextricably linked. A collection of quantum states can have different amounts of quantum entanglement that are possible, and Iosue performed calculations that help quantify if the quantum entanglement values are tightly or loosely clumped together. Entanglement plays a central role in quantum computers, so it is likely to be a key ingredient in any proof that quantum computing’s advantage is real and that a cleverly designed program on a traditional computer can’t possibly compete. 

The calculations that Iosue had performed were only the first of a set that each provide slightly different insights about the entanglement of the analyzed states. Iosue suggested that Youm could perform the other calculations by using the previous work as a guide. Gorshkov agreed, and Youm ended up taking on the project.

“My hope was that the calculations would be similar—like the whole beginning to end process that we did would be similar,” Iosue said. “So, it seemed like a high school student wouldn't have to necessarily dive into too much scientific literature or dive into too much uncertainty. I was hoping there was a bit more of a straight path, but with research, it's not always what you expect.”

Early in the summer, the project hit a snag. Iosue suggested Youm begin with a scientific paper that provided equations that were the natural starting point for the new calculations. But as Youm worked, his results weren’t going anywhere. When the group dug deeper, they determined that the equations in the paper were incorrect, and they had to start over by deriving the initial equations themselves.

Eventually, Youm successfully worked through the math for an additional portion of the calculations, and he also used computer simulations to verify his results.

“In the middle of the project was a lot of coding, mathematical work, and trying to understand the physics processes behind all the math that I was doing,” Youm said. “I worked for around eight hours a day, just trying to progress in my work and deriving the necessary formulas and the theorems. So it was pretty intensive, but also I really enjoyed it.”

In Youm’s science fair project, titled “Measuring Quantum Entanglement Entropy in Gaussian Boson Sampling,” he presented the results and discussed their practical applications to quantum experiments. The calculations apply to Gaussian boson sampling experiments where several measurements collect a sample of results from a specific set of prepared quantum states. Quantum mechanics allows a sample to be designed so that it reflects very specific statistics, and many physicists believe that for many cases it can be prohibitively complex for any computer not exploiting quantum phenomena to create a sample with the correct statistics.

The calculations that Youm performed are not directly used in sampling experiments, but they are a potential tool for studying how entanglement relates to the complexity of the sampling task. Understanding entanglement could be central to definitively proving if a sampling experiment has truly achieved an unassailable quantum advantage.

After the summer, Youm continued to work with the group—scheduling meetings around his normal school schedule and assignments. During the school year, Youm took the lead on writing a paper about the results, which the group has posted on the arXiv preprint server. 

“I've had high school students working with my group in the past, but this was the first time we worked over the summer with a rising junior instead of a rising senior,” said Gorshkov. “Jason's performance was outstanding!”

This summer Youm is once again took on a research project, but this year he was at the 2024 Center for Excellence in Education Research Science Institute summer program at MIT, which accepts 100 high school students from around the world. 

“I am really thankful for Alexey, and the rest of the research group, because without them I wouldn't have been able to get any of these opportunities,” Youm said. “I owe all of this to them, and I just feel really happy and grateful.”

Written by Bailey Bedford

In addition to Gorshkov and Iosue, QuICS Hartree Postdoctoral Fellow Yuxin Wang and JQI graduate student Adam Ehrenberg also worked with Youm and are authors on the paper posted on the arXiv preprint server.

Catching Cosmic Waves

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Published: Monday, February 26 2024 09:24

University of Maryland (UMD) physics Ph.D. student Max Trevor found himself at a crossroads in 2016. Long fascinated by black holes, Trevor studied the enigmatic objects using X-ray astronomy as an undergraduate at the University of Maryland, Baltimore County (UMBC). But as his graduation date grew closer, Trevor wondered how he could take his passion to the next level. 

A groundbreaking announcement helped Trevor make a decision. In February 2016, scientists working on the Laser Interferometer Gravitational-Wave Observatory (LIGO) project announced that for the first time in history, they detected gravitational waves—ripples in spacetime caused by some of the most violent events in the universe, waves that were caused by two black holes colliding with each other billions of light-years away. For Trevor and many other researchers, the Nobel Prize-winning discovery opened up an entirely new way of observing the universe.

“I had some experience with X-rays at UMBC, which I enjoyed,” Trevor recalled. “But hearing about LIGO’s success made me think that gravitational astronomy was going to be the new hot research area for high-energy astrophysics. At that moment, I knew I had to jump in no matter what.”

Knowing that he wanted to pursue gravitational wave research and LIGO science as a graduate student, Trevor found his perfect match at UMD. Attracted by the Department of Physics’ decades-long legacy of gravitational wave research and its continued influence on the field, he joined the lab of Peter Shawhan—a professor of physics and LIGO principal investigator—in spring 2020. Together, they’re working to detect gravitational waves and improve the quality of the data collected by LIGO to ensure its accuracy for all researchers in the community.  

Shawhan, whose work with LIGO stretches back to his time as a postdoctoral researcher at Caltech in 1999, says that the project has come a long way since the announcement of its initial success.

“Today we can laugh and say, ‘Oh, it’s just another regular binary black hole merger,’ but it was a really big deal the first time we were able to detect one,” Shawhan said. “We’re now in the middle of LIGO’s fourth observational run. Thanks to decades of hard work from across the globe and our efforts here at UMD, we can now observe these events every couple of days.” 

Filtering out the noise, keeping the community connected

Detecting gravitational waves in space is no easy task, even now. To do its job, LIGO requires incredibly sensitive instruments called interferometers, which use laser beams to measure minute changes in distance caused by passing gravitational waves. There are currently two interferometers in the United States—one in Louisiana and another in Washington state—and it’s Trevor’s job to weed through the flood of data these interferometers produce, searching for the telltale signs of a gravitational wave event. 

“I write code that performs data analysis in real time. It basically asks, ‘Is this a gravitational wave, yes or no?’ and it tries to match the data points with known profiles of gravitational waves,” Trevor explained. “After that’s done, it repeats the process with the next batch. All this happens in seconds.”

Although interferometers can capture faint signals that come with faraway colliding neutron stars or merging black holes, the instruments are also prone to catching other waves that may not be involved with the cosmos at all—like nearby earthquakes, moving trains or even local weather. Trevor uses tools like machine learning to correlate these irrelevant waves with potential sources and adjusts the detection code to avoid them. According to Shawhan, Trevor’s work is paving the way for upgrades to the LIGO system for future observational runs. 

“Max’s improvements to the algorithms are especially valuable for detecting signals that are particularly challenging to identify,” Shawhan said. “He’s made it easier to separate out irrelevant noise from signals that are made by massive black holes.” 

Trevor is also a major part of the effort to keep astronomers around the world in touch with LIGO’s latest findings. He’s in charge of operating and running a rapid alert software package called Python search for Compact Binary Coalescences (PyCBC). Any time a potential gravitational wave is detected in space, PyCBC feeds information into a system that sends out rapid alerts to astronomers around the world through NASA’s General Coordinates Network—giving them a chance to turn their telescopes to the right part of the sky and potentially catch any visible light from explosive cosmic events. Thanks in part to Trevor’s efforts, PyCBC sends out an alert about once every three days on average, helping to produce over 120 alerts total since LIGO’s current run began.  GCN diagram

“The data is collected, analyzed and sent out really quickly,” Trevor said. “The astronomy community can get preliminary alerts about a possible event within 30 seconds. Timeliness is essential so that scientists can observe the event right as it’s happening and we can form a better understanding of phenomena like black holes and neutron star mergers. It’s really fulfilling for me to play a part in keeping everyone connected.” 

Since joining Shawhan’s lab, Trevor has made significant contributions to LIGO, co-authoring over 30 highly cited papers on the data gathered by the system. As he nears the completion of his doctoral program at UMD, Trevor hopes to continue his work. He believes that his projects, specifically those focused on identifying extraneous noise sources, will play a role in optimizing the next version of LIGO and bring scientists closer to understanding the world beyond Earth. 

“This current observational run is projected to end in June 2025, which is when LIGO will undergo crucial upgrades and changes to make it even more sensitive than previous iterations,” Trevor said. “I’d like to keep doing my part in helping the project stay alive—and supporting the community that seeks to explain how our universe works.”