Harry Dahl Holmgren, 1928-2016

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Category: Department News

Published: Tuesday, October 04 2016 11:03

Professor Emeritus Harry D. Holmgren, who retired from the University of Maryland Department of Physics in 1993, died on September 29, 2016. He was 88.

Prof. Holmgren received his B.S., M.S. and Ph.D. in physics from the University of Minnesota. Following completion of his doctorate in 1954, he was appointed as a physicist at the Naval Research Laboratory, where he worked before joining this Department as an Associate Professor in 1961. In 1965, he was promoted to full Professor and was appointed Director of the UMD Cyclotron Laboratory, a post he held for 13 years. That facility was described in a Washington Post feature article in 1977, citing "man's ageless struggle to unlock the secrets of the universe".

Prof. Holmgren was President of the Southeastern Universities Research Association (SURA) from 1980-87, the crucial period in which that consortium of 31 campuses successfully sought federal funding for the Continuous Electron Beam Accelerator Facility (CEBAF) in the Thomas Jefferson National Accelerator Facility (JLab). During his presidency, he forced the organization to look beyond the accelerator envisioned by the University of Virginia physics group, which was based on old technology. Instead, he persuaded Hermann Grunder from the Lawrence Berkeley National Lab to join the CEBAF group as director, leading to the innovative design of the accelerator. Prof. Holmgren also pushed SURA to consider other possible areas of research; this led to SURAnet, a high-speed communications web among 18 East Coast campuses funded by the NSF and directed by UMD computer scientist Glenn Ricart. Many of today's internet protocols were developed by SURAnet.

Prof. Holmgren was a Fellow of the American Physical Society, and was honored during his career with an AEC Pre-doctoral Fellowship, the E. O. Hulbert Award of the NRL, the Arthur A. Fleming Award for an Outstanding Young Scientist in Government, a NATO Postdoctoral Fellowship and Honorary Membership of the Maryland Academy of Science. He was appointed a Distinguished Visiting Scientist at the University of Paris at Orsay and was a member of Sigma Xi and Phi Beta Kappa.

Prange Prize Awarded Sept. 20, 2016

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Category: Department News

Published: Friday, September 30 2016 21:28

Nobel laureate Frank Wilczek of the Massachusetts Institute of Technology received the 2016 Richard E. Prange Prize and Lectureship in Condensed Matter Theory and Related Areas on September 20, 2016. Prof. Wilczek delivered a public lecture entitled "Some Intersections of Art and Science” and presented a Condensed Matter Theory Center/Joint Quantum Institute seminar entitled “Anyons”.

The Prange Prize, established by the UMD Department of Physics and Condensed Matter Theory Center (CMTC), honors the late Richard E. Prange, whose distinguished professorial career at Maryland spanned four decades (1961-2000). The Prange Prize is made possible by a gift from Prof. Prange's wife, Madeleine Joullié, a Professor of Chemistry at the University of Pennsylvania. Introducing Wilczek was Sankar Das Sarma, who holds the Richard E. Prange Chair in Physics at UMD and is also a Distinguished University Professor and Director of the CMTC.

Profs. Sankar Das Sarma, Madeleine Joullié and Steve Rolston congratulate Frank Wilczek on winning the Richard E. Prange Prize.

UMD Professors & Alumnus Named 2016 Thomson Reuters Citation Laureates

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Category: Department News

Published: Friday, September 23 2016 09:46

UMD Professors & Alumnus Named 2016 Thomson Reuters Citation Laureates

Yorke, Ott, Grebogi named top contenders for Nobel Prize in physics for developing method to control chaos

Two professors and an alumnus from the University of Maryland have been selected as 2016 Thomson Reuters Citation Laureates in physics. The Citation Laureates program uses a variety of criteria, including scientific research citations, to identify the most influential researchers who are likely to win the Nobel Prize.

The Citation Laureate trio includes Edward Ott, UMD Distinguished University Professor in the Department of Electrical and Computer Engineering, Department of Physics, and the Institute for Research in Electronics and Applied Physics; Celso Grebogi, UMD alumnus and the Sixth Century Chair in Nonlinear and Complex Systems at the University of Aberdeen in Scotland; and James A. Yorke, UMD Distinguished University Professor Emeritus in the Department of Mathematics, Department of Physics, and the Institute for Physical Science and Technology.

The scientists received the honor for their description of a control theory of chaotic systems that came to be known as the "OGY method," after the order their last names appeared in their paper describing the method. That paper, which has been cited 4,087 times according to the Web of ScienceTM, was published in the journal Physical Review Letters in 1990.

"Different people have different research goals. One of mine is to have an impact on the way other people work by providing them with interesting new ideas. Perhaps being named being named Citation Laureate is recognition that my collaborators and I are succeeding in that goal," said Yorke, who is known worldwide for coining the term "chaos."

While most researchers try to avoid chaos in physical, chemical or biological systems altogether, Ott, Grebogi and Yorke developed a method to control chaos in such systems and even improve system performance. The basic idea begins with the significant observation that an infinite number of unstable periodic orbits are embedded in a chaotic attractor. To employ the OGY method, one selects an unstable orbit that yields improved performance and stabilizes it by applying small system perturbations to the attractor. However, the perturbation must be tiny compared with the overall size of the attractor to avoid significant modification of the system's natural dynamics.

"Our method renders an otherwise chaotic motion more stable and predictable," said Ott. "It was also the first method to take advantage of the attributes of chaotic dynamics and use them for a specific purpose."

Researchers have used the OGY method to control chaos in a variety of systems, including turbulent fluids, oscillating chemical reactions, magneto-mechanical oscillators and cardiac tissues.

"We are excited, but certainly not surprised, that University of Maryland faculty members and alumni are considered to be in the running for the Nobel Prize in physics," said Jayanth Banavar, dean of the College of Computer, Mathematical, and Natural Sciences at UMD. "Professors Ott, Grebogi and Yorke have authored classic works in the field of chaos theory, with far-reaching impact in areas including meteorology, the life sciences, computer science and economics."

Two UMD physics faculty members previously won the Nobel Prize in physics: Distinguished University Professor William Phillips in 1997 and College Park Professor John Mather in 2006. In addition, UMD alumnus Raymond Davis Jr., B.S. '37, M.S. '39, chemistry, received the Nobel Prize in physics in 2002.

"To appear in the 2016 Citation Laureates is a great honor," said Grebogi. "While we are delighted to be included, it is unlikely that we can compete this year against the Laser Interferometer Gravitational-Wave Observatory (LIGO) gravity experiment, the first direct detection of gravitational waves and a result long awaited since Einstein's prediction of gravity waves in 1916. It is, nevertheless, a privilege to have our work—which opened up a whole new area of research and changed philosophically our way of thinking about chaos—considered in the same company as such a significant breakthrough in physics."

The annual Citation Laureates study has predicted 39 Nobel Prize winners since 2002.

"Highly-cited papers turn out to be one of the most reliable indicators of world-class research, and provides a glimpse at what research stands the best chance at being recognized with a Nobel Prize," said Jessica Turner, global head of government and academia, Intellectual Property and Science, Thomson Reuters.

About UMD's Citation Laureates

Edward Ott received his bachelor's degree in electrical engineering from The Cooper Union in 1963, and M.S. and Ph.D. degrees in electrophysics from The Polytechnic Institute of Brooklyn in 1964 and 1967, respectively. In 1968, he joined the faculty at Cornell University and came to UMD in 1979. He is a fellow of the IEEE, the American Physical Society, the World Innovation Foundation, and the Society for Industrial and Applied Mathematics.

Celso Grebogi, M.S. '75, Ph.D. '78, physics, remained at UMD as a faculty member from 1981 until 2001, with appointments in the Department of Physics, Department of Mathematics, Institute for Plasma Research, and Institute for Physical Science and Technology. After serving as professor at the University of Sao Paulo's Institute of Physics, he joined the University of Aberdeen in 2005. He is a fellow of The Royal Society of Edinburgh, the Brazilian Academy of Sciences, the World Academy of Sciences, the American Physical Society, and the Institute of Physics.

James A. Yorke, Ph.D. '66, mathematics, came to UMD in 1963 as a mathematics graduate student and joined the faculty as an assistant professor in 1967. In 2003, he was awarded the Japan Prize, one of the most esteemed science technology prizes. He is a fellow of the American Physical Society, the American Association for the Advancement of Science, the American Mathematical Society, and the Society for Industrial and Applied Mathematics.

About the University of Maryland

The University of Maryland, the state's flagship institution of higher education, is one of the nation's preeminent public universities. A global leader in research, entrepreneurship and innovation, UMD is home to nearly 38,000 students, 10,000 faculty and staff, and 250 academic programs, and counts more than 344,000 alumni. Its faculty includes three Nobel laureates, three Pulitzer Prize winners, 51 members of the national academies and scores of Fulbright scholars. The institution has a $1.86 billion operating budget and secures $500 million annually in external research funding. For more information about the University of Maryland, visit www.umd.edu.

More information can be found at http://go.umd.edu/if7 or contact Abby Robinson, This email address is being protected from spambots. You need JavaScript enabled to view it..

UMD Physicists Discover “Smoke Rings” Made of Laser Light

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Category: Research News

Published: Friday, September 09 2016 10:24

3D ring structures made by high-intensity lasers could aid the design of powerful microscopes and more efficient telecommunication lines

Most basic physics textbooks describe laser light in fairly simple terms: a beam travels directly from one point to another and, unless it strikes a mirror or other reflective surface, will continue traveling along an arrow-straight path, gradually expanding in size due to the wave nature of light. But these basic rules go out the window with high-intensity laser light. ­­­

Powerful laser beams, given the right conditions, will act as their own lenses and "self-focus" into a tighter, even more intense beam. University of Maryland physicists have discovered that these self-focused laser pulses also generate violent swirls of optical energy that strongly resemble smoke rings. In these donut-shaped light structures, known as "spatiotemporal optical vortices," the light energy flows through the inside of the ring and then loops back around the outside.

The vortices travel along with the laser pulse at the speed of light and control the energy flow around it. The newly discovered optical structures are described in the September 9, 2016 issue of the journal Physical Review X.

The researchers named the laser smoke rings "spatiotemporal optical vortices," or STOVs. The light structures are ubiquitous and easily created with any powerful laser, given the right conditions. The team strongly suspects that STOVs could explain decades' worth of anomalous results and unexplained effects in the field of high-intensity laser research.

"Lasers have been researched for decades, but it turns out that STOVs were under our noses the whole time," said Howard Milchberg, professor of physics and electrical and computer engineering at UMD and senior author of the research paper, who also has an appointment at the UMD Institute for Research in Electronics and Applied Physics (IREAP). "This is a robust, spontaneous feature that's always there. This phenomenon underlies so much that's been done in our field for the past 30-some years."

Orbital angular momentum (OAM) vortices (pink ringlike objects) are three-dimensional laser light structures that rotate around a central beam, much like water circles around a drain. Physicists and engineers have studied this type of laser vortex since the 1990s as a tool to help improve microscopy and telecommunications. Image credit: Howard Milchberg

More conventional spatial optical vortices are well-known from prior research—chief among them "orbital angular momentum" (OAM) vortices, where light energy circulates around the beam propagation direction much like water rotates around a drain as it empties from a washbasin. Because these vortices can influence the shape of the central beam, they have proven useful for advanced applications such as high-resolution microscopy.

"Conventional optical vortices have been studied since the late 1990s as a way to improve telecommunications, microscopy and other applications. These vortices allow you to control what gets illuminated and what doesn't, by creating small structures in the light itself," said the paper's lead author Nihal Jhajj, a physics graduate student who conducted the research at IREAP.

"The smoke ring vortices we discovered may have even broader applications than previously known optical vortices, because they are time dynamic, meaning that they move along with the beam instead of remaining stationary," Jhajj added. "This means that the rings may be useful for manipulating particles moving near the speed of light."

Jhajj and Milchberg acknowledge that much more work needs to be done to understand STOVs, including their physical and theoretical implications. But they are particularly excited for new opportunities that will arise in basic laser research following their discovery of STOVs.

"All the evidence we've seen suggests that STOVs are universal," Jhajj said. "Now that we know what to look for, we think that looking at a high-intensity laser pulse propagating through a medium and not seeing STOVs would be a lot like looking at a river and not seeing eddies and currents."

Eventually, STOVs might have useful real-world applications, like their more conventional counterparts. For example, OAM vortices have been used in the design of more powerful stimulated emission depletion (STED) microscopes. STED microscopes are capable of much higher resolution than traditional confocal microscopes, in part due to the precise illumination offered by optical vortices.

With the potential to travel with the central beam at the speed of light, STOVs could have as-yet unforeseen advantages in technological applications, including the potential to expand the effective bandwidth of fiber-optic communication lines.

"A STOV is not just a spectator to the laser beam, like an angel's halo," explained Milchberg, noting the ability of STOVs to control the central beam's shape and energy flow. "It is more like an electrified angel's halo, with energy shooting back and forth between the halo and the angel's head. We're all very excited to see where this discovery will take us in the future."

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In addition to Jhajj and Milchberg, coauthors on the study include IREAP Associate Research Scientist Jared Wahlstrand and physics/IREAP graduate students Sina Zahedpour , Ilia Larkin and Eric Rosenthal.

The research paper, "Spatio-temporal optical vortices," Nihal Jhajj, Ilia Larkin, Eric Rosenthal, Sina Zahedpour, Jared Wahlstrand, and Howard Milchberg, appears in the September 9, 2016 issue of the journal Physical Review X.

This work was supported by the Defense Advanced Research Projects Agency(Award No. W911NF1410372), the Air Force Office of Scientific Research (Award No. FA95501310044), the National Science Foundation (Award No. PHY1301948), and the Army Research Office (Award No. W911NF1410372). The content of this article does not necessarily reflect the views of these organizations.

Media Relations Contact: Abby Robinson, 301-405-5845, This email address is being protected from spambots. You need JavaScript enabled to view it.

Writer: Matthew Wright

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