Congressman Jamie Raskin of Maryland’s 8th Congressional District will give the fourth Irving and Renee Milchberg Endowed Lecture on Thursday, March 28 at 1 p.m. in the lecture hall (1412) of the John S. Toll Physics Building. Rep. Raskin will discuss Democracy, Autocracy and the Threat to Reason in the 21st Century.

University of Maryland Professor of Physics and Electrical and Computer Engineering Howard Milchberg, his wife Rena, and their three children Moses, Mollie, and Max, established the lecture in memory of Howard's late parents, Renee and Irving Milchberg. Renee and Irving were witnesses to and victims of what can happen to society when ideology and lies are accepted in lieu of facts.

The talk is free and open to the public. Please register: https://science.umd.edu/events/milchberg-2024.html

Rep. Raskin is serving his fourth term representing the eighth district, which includes most of Montgomery County and a small part of Prince George's County.  He is the Ranking Member of the House Committee on Oversight and Accountability in the 118th Congress. 

Rep. Jamie Raskin

Previously Rep. Raskin served three terms on the House Judiciary Committee and the Committee on House Administration. He served two terms on the Rules Committee and the Coronavirus Select Subcommittee. During the 117th Congress he served as Chair of the Oversight Subcommittee on Civil Rights and Civil Liberties and Chair of the Rules Subcommittee on Expedited Procedure. Rep. Raskin was the lead impeachment manager in the second impeachment trial of former president Donald Trump and served on the Select Committee to Investigate the January 6th Attack on the United States Capitol.

Prior to his time in Congress, Raskin was a three-term State Senator in Maryland, where he also served as the Senate Majority Whip. Congressman Raskin is a graduate of Harvard College and Harvard Law School and is a former editor of the Harvard Law Review. He is the author of Unthinkable: Trauma, Truth, and the Trials of American Democracy.

 Irving and Renee Milchberg Endowed Lecture Speakers:

2024:  Congressman Jamie Raskin, "Democracy, Autocracy and the Threat to Reason in the 21st Century"
2023: Jonathan Moreno, University of Pennsylvania, "Bioethics and the Rules-Based International Order"  
2021: James Glanz, reporter for the New York Times, "The Public Relations Machine in Science: A Self-Inflicted Wound?"
2019: Susan Eisenhower, President and CEO of the Eisenhower Institute, "Lessons from 1945: Ethics, the War in Europe, and its Enduring Legacy"

It is with much sadness that the Department of Physics announces the passing of several members of our community.

• Lawrence G. Davies, (B.S., '63), died on November 12, 2023.
• Gordon Leon Hammond (MS), died on August 28, 2023.
• Former professor Jack Leibowitz died on November 4, 2023.
• Professor Emeritus Jean-Paul Richard died on September 6, 2023.
• Wayne Daniel Richardson (B.S., '67) died on November 6, 2023.

Grad school should challenge students’ minds but not their mental health, according to physics graduate students at the University of Maryland who are using scientific principles to understand their peers’ perspectives.

Formed in 2016, the Department of Physics’ Graduate Student Mental Health Task Force (MHTF) is a small, student-led group that conducts surveys to identify the unique challenges faced by physics graduate students. While all of the task force members are researchers, they are also part of the very group they are analyzing.

“When you are studying a population that you yourself are a part of, you come with your own biases, but you also come with an understanding of the group,” said physics graduate student and MHTF member Adam Ehrenberg. “And as somebody who for most of undergrad struggled with their mental health relatively openly, the MHTF seemed like a good way to think about those things in a slightly more official way.”Patrick Banner speaks with colleagues. Credit: Müge Karagöz

The group works together to create surveys and get them approved by the campus Institutional Review Board—a recommended step for research involving human subjects. They then conduct statistical analyses to gather insights, which are condensed into a report and made publicly available online. Some surveys are broadly focused on students’ mental health, while others hone in on a specific issue.

The MHTF’s last report shed light on the high rate of impostor phenomenon among physics graduate students, especially among those who identify as female or nonbinary. People who experience this phenomenon often report feeling like “frauds” who have not earned their spot in a job or academic department. 

Physics graduate student and MHTF member Patrick Banner explained that impostor phenomenon can cause anxiety, depression and low self-esteem, and can even prevent people from pursuing scholarships, fellowships or career opportunities.

“One really harmful aspect of impostor phenomenon is that someone experiencing it may feel that they do not deserve the opportunities they receive and therefore don't pursue them,” Banner said.

Banner said the task force’s next report, slated to publish sometime this semester, will dive deeper into this phenomenon and the role that academic advisors can play in a student’s experience. 

“We had a specific question that we wanted to know, which is: Can the relationship between a student and their advisor affect impostor phenomenon feelings?” Banner said. “We asked not only questions about impostor phenomenon, but also about how students perceived their relationship with their advisor, and we can look at some quantitative correlations between those variables.”

While the MHTF is still analyzing data, preliminary results show that the quality of advising can affect how students view themselves and their place in the physics department. One of the group’s recommendations to advisors is to head off students’ feelings of inadequacy by helping them understand why they might be struggling with a task.

“Grad school is an inherently difficult process to go through, and there are always going to be struggles. Things are going to fail sometimes,” Banner said. “I think the best advisors are good at making that clear and reframing struggles to say, ‘No, it’s not you. This is a hard thing that you’re doing.’”

Steven Rolston, the physics department chair, said the MHTF’s methodical and compassionate approach to mental health has been “gratifying” to witness.

“They address the issue as scientists, using validated tools and raising the levels of statistical analysis as they refine their surveys,” Rolston said. “Simply addressing the topic out in the open—and showing their fellow students that they are not alone and that people do care—can make a big difference.”

The MHTF also produces and manages two resources for grad students: the UMD Physics Grad Student Guide and the Mental Health Resources page on the physics department website. To expand its scope even further, the MHTF started hosting more social events—from movie nights to coffee breaks—to help students feel more connected with their peers. 

In 2021, MHTF members participated in a mental health panel hosted by the American Physical Society and, more recently, shared preliminary results of their newest survey during a meeting of the Chesapeake Section of the American Association of Physics Teachers.

Chandra Turpen, a physics assistant research professor who advises the MHTF, lauded the group’s ability to not only gather data but to effectively share their results with a larger audience.

“This team has consistently done top-notch work—gathering evidence, building relationships with stakeholders across these graduate programs, persuasively communicating their results and making requests to transform our graduate programs,” Turpen said. “Their work embodies many of the best practices for leading inclusive system change efforts.”

Going forward, the group hopes to recruit new students to MHTF—three of the five current members plan to graduate this year. Anyone interested in joining can email the group at . 

And they hope to keep the momentum—and the conversation—going. Erin Sohr (B.S. ’10, physics and astronomy; Ph.D. ’18, physics), who co-founded the MHTF as a graduate student in 2016, said it has been meaningful to see the physics community rally around students’ mental health.

“I think the most important impact is around starting this conversation within the department, normalizing struggles and just making mental health something we notice and talk about together,” said Sohr, who is now a physics assistant research scientist at UMD.

Banner agreed, stressing the value of undertaking these surveys and having difficult conversations.

“Just having the conversation is a way of saying that mental health is a serious issue,” Banner said. “We don’t want to sweep this under the rug. We want everyone to be happy and healthy, so having these conversations is the first step to making that happen.”

Written by Emily Nunez

In day-to-day life, light seems intangible. We walk through it and create and extinguish it with the flip of a switch. But, like matter, light actually carries a little punch—it has momentum. Light constantly nudges things and can even be used to push spacecraft. Light can also spin objects if it carries orbital angular momentum (OAM)—the property associated with a rotating object’s tendency to keep spinning.

Scientists have known that light can have OAM since the early 90s, and they’ve discovered that the OAM of light is associated with swirls or vortices in the light’s phase—the position of the peaks or troughs of the electromagnetic waves that make up the light. Initially, research on OAM focused on vortices that exist in the cross section of a light beam—the phase turning like the propeller of a plane flying along the light’s path. But in recent years, physicists at UMD, led by UMD Physics Professor Howard Milchberg, have discovered that light can carry its OAM in a vortex turned to the side—the phase spins like a wheel on a car, rolling along with the light. The researchers called these light structures spatio-temporal optical vortices (STOVs) and described the momentum they carry as transverse OAM.

“Before our experiments, it wasn’t appreciated that particles of light—photons—could have sideways-pointing OAM,” Milchberg says. “Colleagues initially thought it was weird or wrong. Now research on STOVs is rapidly growing worldwide, with possible applications in areas such as optical communications, nonlinear optics, and exotic forms of microscopy.”

In an article published on Feb. 28, 2024, in the journal Physical Review X, the team describes a novel technique they used to change the transverse OAM of a light pulse as it travels. Their method requires some laboratory tools, like specialized lasers, but in many ways, it resembles spinning a playground merry-go-round or twisting a wrench.Similarities exist between spinning everyday items, like a playground merry-go-round, and spinning vortices of light. Image credit: Martin Vorel

“Because STOVs are a new field, our main goal is gaining a fundamental understanding of how they work. And one of the best ways to do that is to mess with them,” says Scott Hancock, a UMD physics postdoctoral researcher and first author of the paper. “Basically, what are the physics rules for changing the transverse OAM of a light pulse?”

In previous work, Milchberg, Hancock and colleagues described how they created and observed pulses of light that carry transverse OAM, and in a paper published in Physical Review Letters in 2021, they presented a theory that describes how to calculate this OAM and provides a roadmap for changing a STOV’s transverse OAM.

The consequences described in the team’s theory aren’t so different from the physics at play when kids are on a playground. When you spin a merry-go-round you change the angular momentum by pushing it, and the effectiveness of a push depends on where you apply the force—you get nothing from pushing inwards on the axle and the greatest change from pushing sideways on the outer edge. The mass of the merry-go-round and everything on it also impact the angular momentum. For instance, kids jumping off a moving merry-go-round carry away some of the angular momentum, making the merry-go-round easier to stop.

The team’s theory of the transverse OAM of light looks very similar to the physics governing the spin of a merry-go-round. However, their merry-go-round is a disk made of light energy laid out in one dimension of space and another of time instead of two spatial dimensions, and its axis is moving at the speed of light. Their theory predicts that pushing on different parts of a merry-go-round light pulse can change its transverse OAM by different amounts and that if a bit of light is scattered off a speck of dust and leaves the pulse then the pulse loses some transverse OAM with it.

The team focused on testing what happened when they gave the transverse OAM vortices a shove. But changing the transverse OAM of a light pulse isn’t as easy as giving a merry-go-round a solid push; there isn’t any matter to grab onto and apply a force. To change the transverse OAM of a light pulse, you need to flick its phase.

As light journeys through space, its phase naturally shifts, and how fast the phase changes depends on the index of refraction of the material that the light travels through. So Milchberg and the team predicted that if they could create a rapid change in the refractive index at selected locations in the pulse as it flew by, it would flick that portion of the pulse. However, if the entire pulse passes through the area with a new index of refraction, they predicted that there would be no change in OAM—like having someone on the opposite side of a merry-go-round trying to slow it down while you are trying to speed it up.

To test their theory, the team needed to develop the ability to flick a small section of a pulse moving at the speed of light. Luckily, Milchberg’s lab already had invented the appropriate tools. In multiple previous experiments, the group has manipulated light by using lasers for the rapid generation of plasmas—a phase of matter in which electrons have been torn free from their atoms. The process is useful because the plasma brings with it a new index of refraction.

In the new experiment, the team used a laser to make narrow columns of plasma, which they called transient wires, that are small enough and flash into existence quickly enough to target specific regions of the pulse mid-flight. The index of refraction of a transient wire plays the role of a child pushing the merry-go-round.

The researchers generated the transient wire and meticulously aligned all their beams so that the wire precisely intercepted the desired section of the OAM-carrying pulse. After part of the pulse passed through the wire and received a flick, the pulse reached a special optical pulse analyzer the team invented. As predicted, when the researchers analyzed the collected data, they found that the refractive index flick changed the pulse’s transverse OAM.

They then made slight adjustments in the orientation and timing of the transient wire to target different parts of the light pulse. The team performed multiple measurements with the transient wire crossing through the top and bottom of two types of pulses: STOVs that already carried transverse OAM and a second type called a Gaussian pulse without any OAM at all. For the two cases, corresponding to pushing an already spinning or a stationary merry-go-round, they found that the biggest push was achieved by applying the transient wire flick near the top and bottom edges of the light pulse. For each position, they also adjusted the timing of the transient wire laser on various runs so that different amounts of the pulse traveled through the plasma and the vortex received a different amount of kick.Researchers who previously generated vortices of light that they describe as “edge-first flying donuts” have now performed experiments where they disturb the path of the vortices mid-flight to study changes to their momentum. Image credit: Intense Laser-Matter Interactions Lab, UMD

The team also showed that, like a merry-go-round, pushing with the spin adds OAM and pushing against it removes OAM. Since opposite edges of the optical merry-go-round are traveling in opposite directions, the plasma wire could fulfill both roles by changing its position even though it always pushed in the same direction. The group says the calculations they performed using their theory are in excellent agreement with the results from their experiment.

“It turns out that ultrafast plasma provides a precision test of our transverse OAM theory,” says Milchberg. “It registers a measurable perturbation to the pulse, but not so strong a perturbation that the pulse is completely messed up.”

The team plans to continue exploring the physics associated with transverse OAM. The techniques they have developed could provide new insights into how OAM changes over time during the interaction of an intense laser beam with matter (which is where Milchberg’s lab first discovered transverse OAM). The group plans to investigate applications of transverse OAM, such as encoding information into the swirling pulses of light. Their results from this experiment demonstrate that the naturally occurring fluctuations in the index of refraction of air are too slow to change a pulse’s transverse OAM and distort any information it is carrying.

“It's at an early stage in this research,” Hancock says. “It's hard to say where it will go. But it appears to have a lot of promise for basic physics and applications. Calling it exciting is an understatement.”

Story by Bailey Bedford

In addition to Milchberg, and Hancock, graduate student Andrew Goffin and UMD physics postdoctoral associate Sina Zahedpour were co-authors.