Letters From a Science Giant

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Category: Department News

Published: Wednesday, May 22 2019 09:40

A handwritten letter from famed physicist Stephen Hawking to UMD physics Professor Emeritus Charles Misner in the late 1960s is one of the items being auctioned to create an endowment to support study in the field both specialized in—gravitational physics. (Photo by John T. Consoli)

"Dear Charlie,” each letter begins.

They go on to talk about kids, explore recent theoretical ideas and even ask whether reimbursement for a recent trip to the University of Maryland was coming through. Job references are also a big topic—typical for correspondence between two academics.

Far from typical was their author: Stephen Hawking, the brilliant physicist who became a popular author, a science advocate and an international symbol of perseverance in the face of his crippling Lou Gehrig’s disease.

Now the letters—donated by their recipient, UMD physics Professor Emeritus Charles Misner—are being auctioned to create an endowment in the College of Computer, Mathematical, and Natural Sciences.  

Hawking wrote the letters between 1967 and 1970. He’d hit it off with Misner, a fellow physicist studying Einstein’s theory of gravitation, while the American scientist was on a fellowship at the University of Cambridge.

Soon after, Hawking brought his family to Maryland to stay at Misner’s home and spend time at UMD. Misner’s research group was immersed in the theoretical study of gravitation, while UMD Physics Professor Joseph Weber was leading a charge to experimentally detect gravitational waves in space-time—something predicted by Einstein’s theory that even Einstein doubted could be found.

In correspondence that followed the visit, among other things, Hawking asked Misner for job referrals. “Not that I was smarter than him—but I was older,” Misner cracked in a recent interview.

Even in the late ’60s, despite the increasing physical limitations brought on by his ALS, it was clear Hawking was headed for greatness, Misner said. Through the years, the two and their families continued meeting up during fellowships, at conferences and elsewhere, although communication for Hawking became more and more labored, Misner said. Hawking died in March 2018.

Last year, when the Department of Physics was seeking funds for a memorial to Weber—who failed in his personal quest to observe gravitational waves, but laid the critical groundwork for a later experiment that would succeed—Misner remembered the letters. Departmental staff helped ransack his overstuffed office, finally turning up four letters that were auctioned by Christie's, which will create an endowment in honor of Weber to support research in gravitational physics. The auction just closed on May 23, 2019, and the letters sold for a total of 228,750 GBP.  After commissions, this should endow the Weber fund with approximately $260,000.

To contribute to the Weber fund, click here: https://giving.umd.edu/giving/fund.php?name=weber-endowment-for-gravitational-physics

Original story by Chris Carroll.

High-resolution Imaging Technique Maps out an Atomic Wave Function

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Category: Research News

Published: Monday, May 20 2019 09:41

Overlapping Laser Beams Offer a New Way to Extract A Quantum System's Essential Information

The team has used laser light to construct an image of an atomic wave function (shown in purple). The graphic is an artistic depiction of this process, showing a microscope objective trained on atoms (spheres) suspended in an optical lattice (tall white waves). The team's technique reveals information about an atomic wave function in unprecedented detail.

From NIST News

JQI researchers have demonstrated a new way to obtain the essential details that describe an isolated quantum system, such as a gas of atoms, through direct observation. The new method gives information about the likelihood of finding atoms at specific locations in the system with unprecedented spatial resolution. With this technique, scientists can obtain details on a scale of tens of nanometers—smaller than the width of a virus.

The new experiments use an optical lattice—a web of laser light that suspends thousands of individual atoms—to determine the probability that an atom might be at any given location. Because each individual atom in the lattice behaves like all the others, a measurement on the entire group of atoms reveals the likelihood of an individual atom to be in a particular point in space.  

Published in the journal Physical Review X, the technique (similar work was published simultaneously by a group at the University of Chicago) can yield the likelihood of the atoms’ locations at well below the wavelength of the light used to illuminate the atoms—50 times better than the limit of what optical microscopy can normally resolve. 

“It’s a demonstration of our ability to observe quantum mechanics,” says JQI Fellow and NIST physicist Trey Porto, one of the researchers behind the effort. “It hasn’t been done with atoms with anywhere near this precision.”

To understand a quantum system, physicists talk frequently about its “wave function.” It is not just an important detail; it’s the whole story. It contains all the information you need to describe the system.   

“It’s the description of the system,” says JQI Fellow and UMD physics professor Steve Rolston, another of the paper’s authors. “If you have the wave function information, you can calculate everything else about it—such as the object’s magnetism, its conductivity and its likelihood to emit or absorb light.”

While the wave function is a mathematical expression and not a physical object, the team’s method can reveal the behavior that the wave function describes: the probabilities that a quantum system will behave in one way versus another. In the world of quantum mechanics, probability is everything. 

Among the many strange principles of quantum mechanics is the idea that before we measure their positions, objects may not have a pinpointable location. The electrons surrounding the nucleus of an atom, for example, do not travel in regular planetlike orbits, contrary to the image some of us were taught in school. Instead, they act like rippling waves, so that an electron itself cannot be said to have a definite location. Rather, the electrons reside within fuzzy regions of space.

All objects can have this wavelike behavior, but for anything large enough for unaided eyes to see, the effect is imperceptible and the rules of classical physics are in force—we don’t notice buildings, buckets or breadcrumbs spreading out like waves. But isolate a tiny object such as an atom, and the situation is different because the atom exists in a size realm where the effects of quantum mechanics reign supreme. It’s not possible to say with certainty where it’s located, only that it will be found somewhere. The wave function provides the set of probabilities that the atom will be found in any given place. 

Quantum mechanics is well-enough understood—by physicists, anyway—that for a simple-enough system, experts can calculate the wave function from first principles without needing to observe it. Many interesting systems are complicated, though.

“There are quantum systems that can’t be calculated because they are too difficult,” Rolston says—such as molecules made of several large atoms. “This approach could help us understand those situations.”

As the wave function describes only a set of probabilities, how can physicists get a complete picture of its effects in short order? The team’s approach involves measuring a large number of identical quantum systems at the same time and combining the results into one overall picture. It’s sort of like rolling 100,000 pairs of dice at the same time—each roll gives a single result, and contributes a single point on the probability curve showing the values of all the dice. 

What the team observed were the positions of the roughly 100,000 atoms of ytterbium the optical lattice suspends in its lasers. The ytterbium atoms are isolated from their neighbors and restricted to moving back and forth along a one-dimensional line segment. To get a high-resolution picture, the team found a way to observe narrow slices of these line segments, and how often each atom showed up in its respective slice. After observing one region, the team measured another, until it had the whole picture.

Rolston says that while he hasn’t yet thought of a “killer app” that would take advantage of the technique, the mere fact that the team has directly imaged something central to quantum research fascinates him. 

“It’s not totally obvious where it will be used, but it’s a new technique that offers new opportunities,” he said. “We’ve been using an optical lattice to capture atoms for years, and now it’s become a new kind of measurement tool.” 

The original story was written by C. Boutin/NIST. Minor modifications were made for posting to this website.

Professors Chris Monroe and Jake Taylor Describe the National Quantum Initiative in Science Magazine

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Category: Department News

Published: Friday, May 10 2019 16:20

A semiconductor chip ion trap, fabricated by Sandia National Laboratories, is composed of gold-plated electrodes that suspend individual atomic ion qubits above the surface of the chip. The chip (bow-tie shape) is about 10 mm across. The inset is a magnified image of 80 atomic 171Yb+ ions glowing from scattered laser radiation. PHOTO: KAI HUDEK/UMD/IONQ AND E. EDWARDS/JQIUMD physics professors Christopher Monroe and Jake Taylor, together with Michael Raymer of the University of Oregon, published an article on the National Quantum Initiative (NQI) in the May 3 issue of Science. The NQI Act, which was signed into law on December 21, 2018, lays out a plan for the National Institute of Standards and Technology, the National Science Foundation, and the Department of Energy to work with academia and industry to further grow the quantum information science and technology (QIST) sector. Earlier this year, Monroe and Raymer wrote an article on the NQI for the February 2019 issue of Quantum Science and Technology, which details some of the events that ultimately led to this law.

The new article describes how the NQI aims to enable a so-called QIST ecosystem to study and overcome scientific challenges in this area, as well as build up a workforce educated in quantum science. Some of the possible outcomes of the NQI could include improved sensors, universally programmable quantum computers, and a more secure global communication network. The article also briefly summarizes possible risks associated with quantum research and development, including possible failure modes of the technology, as well as unforeseen ethical questions.

Monroe is the Bice-Seci Zorn Professor of Physics, a Distinguished University Professor, Fellow of the Joint Quantum Institute (JQI) and the Joint Center for Quantum Information and Computer Science (QuICS). He also co-founded the quantum computing company IonQ. Monroe previously advocated for a NQI through the National Photonics Initiative and testified before a joint congressional committee hearing on the topic of American Leadership in Quantum Technology in 2017. A second JQI and QuICS Fellow Carl Williams, who is Acting Director of the Physical Measurement Laboratory at NIST, provided expert testimony to congress at that same hearing.

Taylor is an adjunct professor in the Department of Physics, Co-Director of the Joint Center for Quantum Information and Computer Science and Fellow of the Joint Quantum Institute and the National Institute of Standards and Technology. He is also the Assistant Director for Quantum Information Science at the Office of Science and Technology Policy and was recently named the Interim Director for the National Quantum Coordination Office, which was established as part of the NQI.

Raymer is a Knight Professor of Liberal Arts and Sciences of the Oregon Center for Optical, Molecular and Quantum Science at the University of Oregon. Raymer has also been a strong advocate for developing a national strategy around QIST.

Three Physics Undergraduates Named 2019 Goldwater Scholars

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Category: Department News

Published: Thursday, May 09 2019 09:47

Three University of Maryland physics undergraduates have been awarded scholarships by the Barry Goldwater Scholarship and Excellence in Education Foundation, which encourages students to pursue advanced study and research careers in the sciences, engineering and mathematics. 

Over the last decade, UMD’s nominations yielded 33 scholarships—the most in the nation, followed by Stanford University with 29. Harvard University, the Massachusetts Institute of Technology and Johns Hopkins University also rank in the top 10. The campus Goldwater Scholarship nominating process has been led since 2001 by Robert Infantino, associate dean of undergraduate education in the College of Computer, Mathematical, and Natural Sciences.

John Martyn, Nicholas Poniatowski and Mark Zic were among the 496 Barry Goldwater Scholars selected from 1,223 students nominated nationally this year. All three students plan to pursue Ph.D. degrees.

Yaelle Goldschlag, a sophomore seeking double degrees in computer science and mathematics at UMD, also recieved the prestigious scholarship.

John Martyn. Photo: Faye LevineJohn Martyn—a junior majoring in physics and a member of the University Honors Program in the Honors College—is interested in quantum information and quantum matter. One of his interests is quantum computing, which may solve some problems far faster than classical computers.

Since 2017, Martyn has worked with Physics Assistant Professor Brian Swingle on various aspects of quantum information. Martyn developed a method to prepare approximations to thermal states, which describe quantum systems in contact with a heat bath of a given temperature. Martyn’s method may one day enable quantum computers to study quantum matter systems and models of black holes. Martyn presented this work at the 2019 American Physical Society March Meeting and the 2019 National Collegiate Research Conference.

“John really strives for perfection in his work and has already demonstrated many of the skills needed to function as an independent researcher,” Swingle said.

In addition, Martyn helped administer the high energy physics computing cluster at UMD. Working with Shabnam Jabeen, a lecturer in the Department of Physics who manages the cluster, Martyn simulated the production of theoretical particles that may result from experiments performed using the Large Hadron Collider at CERN, the European particle physics laboratory in Geneva, Switzerland.

In summer 2018, Martyn conducted research with the Laser Interferometer Gravitational-Wave Observatory (LIGO) team at the California Institute of Technology, where he investigated quantum noise in LIGO’s gravitational wave detectors. Martyn constructed optical components and other electronics for a prototype detector with improved sensitivity. For this work, Martyn received the 2018 Carl Albert Rouse Undergraduate Research Fellowship from the National Society of Black Physicists.

Other awards Martyn received include the 2018 Angelo Bardasis Scholarship from the UMD Department of Physics and the 2016 Mary-Kathryn Abernathy Memorial Scholarship from the Community Foundation of Howard County.

Martyn is a member of the UMD chapter of the Society of Physics Students and the National Society of Black Physicists. He is also president of the UMD Skateboarding Club. 

Nicholas Poniatowski. Photo: Faye LevineNicholas Poniatowski—a junior majoring in physics—is interested in the study of superconductivity in unconventional materials.

Superconductors are valued for their ability to conduct electricity without resistance. However, conventional superconductors must be cooled to temperatures below -200 degrees Celsius. This makes current superconductor technology impractical for real-world applications, such as smart power grids, power storage units and imaging systems.

Working with UMD Physics Professor Richard Greene at the Center for Nanophysics and Advanced Materials, Poniatowski studies a family of copper-oxide materials called cuprates—high-temperature superconductors that can exhibit superconductivity closer to room temperature.

In one project, Poniatowski and his collaborators found that a particular cuprate responded in unexpected ways to variations in temperature and magnetic field. Their findings may offer clues to the origin of high-temperature superconductivity in cuprates. This work will be published on May 17, 2019, in the journal Science Advances. Poniatowski presented additional results related to this work at the 2019 APS March Meeting. 

To further characterize high-temperature superconductors, Poniatowski also used quantum tunneling—a quantum phenomenon that can help scientists study materials at the atomic level—to probe the microscopic properties of cuprates.

In addition, Poniatowski is the sole author of an article, forthcoming in the American Journal of Physics, describing the theoretical relationship between superconductivity and the Higgs mechanism in the standard model.

“Nick is extraordinary at both theory and experiment, a combination of skills that is very rarely seen,” said Greene. “He has tremendous potential for significant experimental research contributions in the future.”

In addition to conducting research, Poniatowski served as a teaching assistant for PHYS 272: “Introductory Physics: Fields” and PHYS 441: “Introduction to Sub Atomic Physics.” During summer 2018, he served as a mentor with the Louis Stokes Alliances for Minority Participation. 

Mark Zic. Photo: Faye LevineMark Zic—a junior majoring in physics and a member of the University Honors Program in the Honors College—is interested in the study of topological materials and superconductors, which have potential applications in quantum computing.

Working with Johnpierre Paglione, professor of physics and director of the Center for Nanophysics and Advanced Materials, Zic conducts quantum materials research. He helped discover and characterize a novel potential superconductor that may one day help quantum computers store information more robustly. This study was published in the journal Physical Review B in 2018. 

In addition, Zic led an effort to use the UMD Radiation Facilities to irradiate quantum materials to characterize their physical properties for potential use in quantum technologies. He helped uncover how to study disorder on the atomic level in superconducting materials, which will help scientists understand the fundamental mechanism behind superconductivity. Zic presented this work at the 2018 Canadian Institute for Advanced Research Quantum Materials Summer School and Program Meeting.

Zic also assisted in experiments using ultracold temperatures to characterize a new superconductor that survives under extremely high magnetic fields. This work has been accepted for publication in the journal Science.

“Mark has continued to surprise me with his abilities, initiative and progress,” Paglione said. “He has engaged in not one, but three graduate or even postgraduate level projects in the last year and shows no signs of slowing down. He is a true asset to our center.”

Zic currently serves as a teaching assistant for PHYS 273: “Introductory Physics: Waves” and previously served as a teaching assistant for three other physics courses. In 2018, his outstanding performance as a teaching assistant earned him an honorable mention for the UMD Department of Physics’ Ralph Myers & Friends of Physics Award. In 2017, Zic served as a mentor for Foundational Learning and Mentorship Experience (previously Science Enrichment After School), a student-led program that teaches after-school physics classes to students at Adelphi Elementary School in Adelphi, Maryland.

In addition, Zic received the 2016 Angelo Bardasis Scholarship from the UMD Department of Physics from 2016 to 2019.

The Goldwater Scholarship program was created in 1986 to identify students of outstanding ability and promise in science, engineering and mathematics, and to encourage their pursuit of advanced study and research careers. The Goldwater Foundation has honored 66 University of Maryland winners and five honorable mentions since the program’s first award was given in 1989.

Colleges and universities may submit up to four nominations annually for these awards. Goldwater Scholars receive one- or two-year scholarships that cover the cost of tuition, fees, books, and room and board up to $7,500 per year. These scholarships are a stepping-stone to future support for the students’ research careers.