News

Postings created for publication in the Physics Department web page news feed.

Astronomer Jonathan Trump interviewed on UConn 360

UConn Astrophysicist and observational astronomer Jonathan Trump was a recent guest on UConn 360, a podcast from the Storrs campus of the University of Connecticut. In this conversation, Jonathan tells about how attending a lecture as an undergraduate at Penn State captured his interest and changed the course of his professional career. Now Jonathan offers similar career-changing opportunities to UConn students, who just this year have applied for and obtained dedicated time for observations by the Hubble space telescope.

Greetings from the Department Head

New building, new teaching approach, new people – there is a lot of change and excitement in the air for the Physics Department in 2019. The most obvious change is that physics has moved into a newly renovated building. What most alumni will remember as the Math Building has been taken down to its frame and rebuilt as the new physics building, formally Gant South. The new building features large windows with lots of light, revamped teaching labs, and a theory suite at the east end of each hallway. There are also plenty of meeting rooms and nooks, complete with writing spaces, to foster spontaneous discussions. We moved into the offices and teaching spaces at the start of fall semester, whereas the research lab relocations are ongoing as I write.

Along with the new building comes new teaching laboratories. The most striking of these are our studio-labs, located in the Gant Plaza building in the center of the Gant Complex. These studio labs have allowed us to redesign how we teach our introductory physics with calculus courses. Instead of three one-hour lectures per week and a three hour lab, there are now three two-hour meetings per week with mixed activities. The rooms are arranged with groups sitting around tables, and class time is spent on group efforts to explore concepts, solve problems, and conduct laboratory measurements. We have been developing this program using the Phys 1601 and 1602 courses for physics majors. This fall we rolled out the first of four other courses to be taught in this method with Phys 1501, to be followed in successive semesters by Phys 1502, Phys 1401, and Phys 1402.

If your travels bring you to the Storrs area, please stop by our new building. I will give anyone interested a tour myself if my schedule allows.

We also have several new faces around the department this fall. We have hired two new assistant professors in astrophysics, Chiara Mingarelli and Daniel Angles-Alcazar. Both have been hired in a bridge program with the Flatiron Institute of the Simons Foundation. Simons is the leading philanthropic foundation focused on science, and the four centers hosted at the Flatiron are world leaders in computational methods. We also have two new full-time teaching faculty, Niraj Ghimire and Sarah Trallero. Niraj was our own Ph.D. student who had previously worked on our Studio Physics development team. Sarah has been working with our teaching lab support team, with previous experience at Kansas State teaching studio-style physics courses. We have several new members of our teaching lab support team, with three new technicians. Zach Transport and James Jaconetta began working with us last January, and Hannah Morrill joined us over the summer. And finally, while I am not a new face, I took over as department head about a year ago and this is my first go-round writing a welcome to our newsletter. I would like to personally thank Professor Nora Berrah, our past department head, for putting our department on a firm footing that has made my job much easier.

Barry Wells

Professor Jocelyn Bell Burnell – 2019 Katzenstein Lecturer

The UConn Physics Department is delighted to announce that our 2019 Distinguished Katzenstein Lecturer will be Professor Dame Jocelyn Bell Burnell. The lecture will take place on Friday November 8.

Professor Dame Jocelyn Bell Burnell (pictured at left) is world famous for her discovery of pulsars in 1967. Pulsars are a special type of neutron star, the rotating dense remnant of a massive star. Pulsars have highly magnetic surfaces and emit a beam of electromagnetic radiation along their poles. This beam of light moves into and out of our line-of-sight at quick, constant intervals, appearing as a regular “pulse” of light.

At the time of this discovery, Bell Burnell was a graduate student at the University of Cambridge and worked with her supervisor, Anthony Hewish, to construct the Interplanetary Scintillation Array to study another class of objects called quasars. In the course of her daily detailed analysis, she noticed a strange “pulsing” signal in her data. Jokingly dubbed “Little Green Man 1” (LGM-1), further data-taking and analysis revealed this signal to be rapidly spinning neutron star, eventually dubbed a “pulsar.”

Bell Burnell’s discovery is considered one of the most important achievements of the 20th century and was recognized by a Nobel Prize in Physics in 1974, awarded to her supervisor Anthony Hewish as well as to astronomer Martin Ryle. While many condemned the omission of Bell Burnell for the award, she rose above, graciously stating, “I believe it would demean Nobel Prizes if they were awarded to research students, except in very exceptional cases, and I do not believe this is one of them. Finally, I am not myself upset about it – after all, I am in good company, am I not!”

Professor Dame Jocelyn Bell Burnell has a highly distinguished career. Some notable highlights include serving as head of the Royal Astronomical Society and as the first female president of both the Institute of Physics and The Royal Society of Edinburgh. She was appointed Dame Commander of the Order of the British Empire for services to astronomy in 2007. Her story has been featured in a number of works, including the BBC Four’s Beautiful Minds and BBC Two’s Horizon. Bell Burnell is currently the chancellor of the University of Dundee in Scotland and a visiting professor of astrophysics at the University of Oxford.

In 2018 Bell Burnell was awarded a Special Breakthrough Prize in Fundamental Physics. Only four such prizes have been awarded, one to Stephen Hawking, one to the CERN scientists who discovered the Higgs Boson, and one to the LIGO team for their detection of gravitational waves. This award recognizes her discovery of pulsars and “a lifetime of inspiring scientific leadership.” In addition to her research accolades, her teaching, leadership, and work to lift up women and minorities in science is without parallel.

Breaking Up is Hard To Do (for Electrons in High Temperature Superconductors)

Physics researcher Ilya Sochnikov next to a dilution refrigerator in the Gant Complex on July 16, 2019. (Sean Flynn/UConn Photo)

Physicists used to think that superconductivity – electricity flowing without resistance or loss – was an all or nothing phenomenon. But new evidence suggests that, at least in copper oxide superconductors, it’s not so clear cut.

Superconductors have amazing properties, and in principle could be used to build loss-free transmission lines and magnetic trains that levitate above superconducting tracks. But most superconductors only work at temperatures close to absolute zero. This temperature, called the critical temperature, is often only a few degrees Kelvin and requires liquid helium to stay that cold, making such superconductors too expensive for most commercial uses. A few superconductors, however, have a much warmer critical temperature, closer to the temperature of liquid nitrogen (77K), which is much more affordable. 

Many of these higher-temperature superconductors are based on a two-dimensional form of copper oxide. 

“If we understood why copper oxide is a superconductor at such high temperatures, we might be able to synthesize a better one” that works closer to room temperature (293K), says UConn physicist Ilya Sochnikov.

Sochnikov and his colleagues at Rice University, Brookhaven National Lab and Yale recently figured out part of that puzzle, and they report their results in the latest issue of Nature.

Their discovery was about how electrons behave in copper oxide superconductors. Electrons are the particles that carry electric charge through our everyday electronics. When a bunch of electrons flow in the same direction, we call that an electric current. In a normal electric circuit, say the wiring in your house, electrons bump and jostle each other and the surrounding atoms as they flow. That wastes some energy, which leaves the circuit as heat. Over long distances, that wasted energy can really add up: long-distance transmission lines in the U.S. lose on average 5% of their electricity before reaching a consumer, according to the Energy Information Administration. 

But in a superconductor below its critical temperature, electrons behave totally differently. Instead of bumping and jostling, they pair up and move in sync with the other electrons in a kind of wave. If electrons in a normal current are a rushing, uncoordinated mob, electrons in a superconductor are like dancing couples, gliding across the floor like people in a ballroom. It’s this friction-free dance – coherent motion – of paired electrons that makes a superconductor what it is.

The electrons are so happy in pairs in a superconductor that it takes a certain amount of energy to pull them apart. Physicists can measure this energy with an experiment that measures how big a voltage is needed to tear an electron away from its partner. They call it the ‘gap energy’. The gap energy disappears when the temperature rises above the critical temperature and the superconductor changes into an ordinary material. Physicists assumed this is because the electron pairs have broken up. And in classic, low-temperature superconductors, it’s pretty clear that that’s what’s happening.

But Sochnikov and his colleagues wanted to know whether this was really true for copper oxides. Copper oxides behave a little differently than classic superconductors. Even when the temperature rises well above the critical level, the energy gap persists for a while, diminishing gradually. It could be a clue as to what makes them different.

The researchers set up a version of the gap energy experiment to test this. They made a precise sandwich of two slices of copper oxide superconductor separated by a thin filling of electrical insulator. Each slice was just a few nanometers thick. The researchers then applied a voltage between them. Electrons began to tunnel from one slice of copper oxide to the other, creating a current.

By measuring the noise in that current, the researchers found that a significant number of the electrons seemed to be tunneling in pairs instead of singly, even above the critical temperature. Only about half the electrons tunneled in pairs, and this number dropped as the temperature rose, but it tapered off only gradually.

“Somehow they survive,” Sochnikov says, “they don’t break fully.” He and his colleagues are still not sure whether the paired states are the origin of the high-temperature superconductivity, or whether it’s a competing state that the superconductor has to win out over as the temperature falls. But either way, their discovery puts a constraint on how high temperature superconductors happen.

“Our results have profound implications for basic condensed matter physics theory,” says co-author Ivan Bozovic, group leader of the Oxide Molecular Beam Epitaxy Group in the Condensed Matter Physics and Materials Science Division at the U.S. Department of Energy’s Brookhaven National Laboratory and professor of applied physics at Yale University. Sochnikov agrees.

“There’s a thousand theories about copper oxide superconductors. This work allows us to narrow it down to a much smaller pool. Essentially, our results say that any theory has to pass a qualifying exam of explaining the existence of the observed electron pairs,” Sochnikov says. He and his collaborators at UConn, Rice University, and Brookhaven National Laboratory plan to tackle the remaining open questions by designing even more precise materials and experiments. 

The research work at UConn was funded by the State of Connecticut through laboratory startup funds.

This article first appeared on UConn Today, August 21, 2019.

Daniel McCarron wins NSF Early Career Award

Daniel McCarron, assistant professor of physics, the College of Liberal Arts and Sciences, will receive $645,000 over five years for his work on the development of techniques to trap large groups of molecules and cool them to temperatures near absolute zero. The possible control of molecules at this low temperature provides access to new research applications, such as quantum computers that can leverage the laws of quantum mechanics to outperform classical computers.

The NSF Faculty Early Career Development (CAREER) Program supports early-career faculty who have the potential to serve as academic role models in research and education, and to lead advances in the mission of their department or organization. Activities pursued by early-career faculty build a firm foundation for a lifetime of leadership in integrating education and research.

McCarron was one of 8 junior faculty at the University of Connecticut to receive the prestigious Early Career awards from NSF in 2019. For a description of all 8 awards, see this recent article published in UConn Today.

Meet the Researcher: Carlos Trallero

 – Anna Zarra Aldrich ’20 (CLAS), Office of the Vice President for Research

When Carlos Trallero started his academic career in physics, he had no idea he would become a pioneer in a field of research that uses high-power lasers to investigate atomic and molecular physical phenomena.

Originally from Cuba, where there isn’t much funding for experimental research, Trallero began his academic career by studying theoretical physics. But as a senior graduate student at Stony Brook University, he got the chance to work in a lab doing experimental work and quickly recognized it was his true passion.

“I talked to a professor doing experimentation with ultra-fast lasers and I fell in love with it. And at first, I sucked at it — I was horrible,” says the professor of physics who is now working with four research grants funding separate investigations.

Trallero works with very short laser beams, with an emphasis on very short. The lasers he uses can pulse with attosecond precision. As a comparison, there are as many attoseconds in one second as there have been seconds in the entire history of the universe since the Big Bang.

It takes light half an attosecond to cross the orbit of hydrogen, the smallest atom. When trying to study something that fast, scientists need the kind of precision the lasers Trallero can offer. The goal of this research is to gain a better understanding of how electrons, one of the fundamental atomic building blocks in the universe, move and react to light. By understanding the physics of electron movement, scientists could improve the design of technologies like superconductors.

“The dream is to be able to perform logistical operations like a computer at the attosecond level,” Trallero says. “It would really advance computational speeds. If you could make as many calculations in a second as there have been seconds in the history of the universe – that’s an astounding number.”

His lab is now working to break the attosecond barrier into the zeptosecond barrier which is 1,000 times faster than the attosecond.

While some of the potential applications of this research remain unknown since the field is still in its infancy, Trallero views the premise of his research as creating basic knowledge. He is investigating the atomic and molecular phenomena which determine so many things in our universe but about which we still know relatively little.

From left to right, Edward McManus Michael Davino Carlos Trallero Brandin Davis Zhanna Rodnova Tobias Saule Rich Sadlon (Submitted Photo)
Members of Trallero’s lab from left to right, Edward McManus, Michael Davino, Carlos Trallero, Brandin Davis, Zhanna Rodnova, Tobias Saule, Rich Sadlon. (Carson Stifel (’21 CLAS)/UConn Photo)

One project funded by the Department of Energy has Trallero looking at the properties of atoms and molecules in the quantum world by harnessing light waveforms at the attosecond time scale through interferometry. Interferometers provide precise measurements of molecules using two beams of light which interfere with each other. The images produced by this technology will allow Trallero to find out information about the rotational dynamics of molecules.

“In the quantum world, properties of atoms and molecules are not as simple as in the real world,” says Trallero.

Another of Trallero’s grants, from the U.S. Air Force Office of Scientific Research, involves creating an incredibly bright beam. Trallero’s lab is working on taking electrons out of nanoparticles and then sending them back in, which will produce a bright, energetic light. “The process to study these dynamics has never been executed in this manner,” Trallero says.

Trallero is also working on two grants from the U.S. Navy,  including one that aims to develop infrared “body heat lasers.”

Through these grants, Trallero is developing a new class of laser which is only comparable to those found at large, multinational laser facilities like the European Light Infrastructure. Compared to the technology currently available to Trallero at UConn, this new class of laser will have almost 20 times more average power than the current laser.

Developing a laser of this caliber will be incredibly useful for studying phenomena that only occur a few times per shot of the laser in real time. The laser will enable researchers to probe the molecules with X-rays and ultraviolet rays to look at their structure and is being developed through a partnership with a Canadian company, Few-cycle, and a German company, Amphos. Researchers like Trallero are able to get advanced technology for a fraction of their retail value by doing research of interest for these companies, which are constantly trying to innovate in step with the science.

“We’re only paying a fraction of the price because the company is interested in showing they can develop this kind of technology,” Trallero says. “Showing they have the capacity and showcasing what we do with, and for, them helps them gain a customer base and it helps us make major advances in basic science at the same time.”

Trallero is also considering creating spin-off tech companies based on his university inventions with graduate students and postdocs. He has developed nanoparticle technology which can help transform molecules from a liquid to a gaseous state which could be beneficial for producing aerosols.

Trallero views physics as “the broadest science” since it has unique applications to math, engineering, chemistry and, even, biology. “I try to think about particular scientific questions in a different way than perhaps other people who have been working in this field for a long time do,” Trallero says. “Often we suffer from too much in-depth specialization.”

He wants to make use of the tools from every specialty he can, and he instills this same inclination in the students working in his lab.

“They don’t know what they’re going to face in the future and by having a broad skill set and a broad mindset they’ll be prepared for anything,” Trallero says. “You’re opening your mind to more possibilities.”

This article first appeared on UConn Today, August 19, 2019

International Summer School “Strong interactions beyond simple factorization”

May 27-June 5 UConn Physics Department hosted an international summer school Strong interactions beyond simple factorization: collectivity at high energy from initial to final state. The school was supported by an NSF grant to Prof. Kovner and was devoted to modern approaches to the physics of high energy hadronic and heavy ion collisions.

Amelia Henkel, Graduating President of the Undergraduate Women in Physics Club, speaks about her time at UConn

 

Amelia Henkel, graduating Double Major in Physics and Human Rights, and President of the Undergraduate Women in Physics Club, speaks on the CLAS website about her passion for physics and human rights, and how she mastered challenges in her remarkably interdisciplinary curriculum. “We really need to interact with other disciplines,” says Amelia, “because that’s when physics has the opportunity to make a real impact on the rest of the world.” Her broad research interests range from A to W: from Astronomy to Women’s, Gender, and Sexuality Studies. “Respecting and promoting human rights is a prerequisite to realizing our full potential as human beings,” says Amelia. Physics as a discipline has made progress to become more inclusive, but many groups remain minorities including women. In daily college life in physics departments female students still face “microaggressions and discriminatory practices” which are often unintended and unconscious but nonetheless damaging and frustrating.  As the President of the Undergraduate Women in Physics Club, Amelia helped to organize “events that promote community cohesion and inform the students about the nature of some of the barriers that exist in physics and in STEM, while talking about how we can overcome them.” The recent department-wide event Women in Physics Colloquium organized by Amelia was thought provoking and well-received. The percentage of women earning a Bacheleor’s Degree in Physics from UConn, though slowly increasing and compatible with the national average of about 20% published by APS, is far away from where we wish to be. But the efforts of students like Amelia contribute to improving the situation.  Many thanks to Amelia whose commitment helps to make our department better.

Read more about Amelia on the CLAS website. A short summary of her story is in UConn Today.

2019 Pollack Lecture

On April 11th and 12 of 2019 Prof. Paul Corkum of the Joint Attosecond Laboratory (University of Ottawa and the National Research Council of Canada) visited the department. Prof. Corkum’s main area of research is on the interaction of ultrashort laser pulses with matter broadly defined. His most notable contribution is perhaps the discovery of the so-called three-step model, which has become the basis of the emerging field of attosecond science. Attoseconds, equal to 1 billionth of 1 billionth of a second (10-18 s) is the shortest time scale ever measured or controlled by humans and is at the forefront of modern optics.

Prof. Corkum is a member of the US National Academy of Sciences, the Russian Academy of Sciences, the Austrian Academy of Sciences, the Royal Canadian Academy of Sciences and the Royal Society of London. He has received many accolades throughout his career, including the Thomson Reuters Citation Laureate which is awarded to researchers who are “of Nobel class” and likely to earn the Nobel someday and the Order of Canada.

On April 12, Prof. Corkum presented the annual Edward Pollack Distinguished Lecture, entitled “Attosecond Pulses Generated in Gases and Solids”. This lecture is supported by an endowment established by the family of the late Professor Edward Pollack in 2005. Ed’s family, friends and colleagues made contributions in his memory. This special colloquium provides a presentation in Ed’s honor in the field of atomic, molecular and optical physics, his area of research expertise. This year Mrs. Rita Pollack and their three children: Cindy [U.S. Government civil servant], Lois [now a professor of applied physics at Cornell], and Howard [professor of modern languages (German) at dePauw University in Indiana] were all in attendance.

Below, dinner with the Pollack family members, UConn faculty, and guests.

Clockwise from left: Victoria Starzef, George Gibson, Win Smith, Anne Smith, Margaret Kessel, Quentin Kessel, Nadia Corkum, Paul Corkum, Robin Côté, Lois Pollack, Cindy Blazar, Rita Pollack, Howard Pollack-Milgate, Sophie Pollack-Milgate, and Sarah Trallero

 

Astronomers Assemble View of Evolving Universe

 – Donna Weaver & Ray Villard, Space Telescope Science Institute

The University of Connecticut’s Katherine Whitaker is part of a team of astronomers who have put together the largest and most comprehensive “history book” of the universe from 16 years’ worth of observations from NASA’s Hubble Space Telescope.

This image, a mosaic of nearly 7,500 separate Hubble exposures, presents a wide portrait of the distant universe and contains roughly 265,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the universe’s birth in the Big Bang. (Space Telescope Science Institute Image)

The deep-sky mosaic provides a wide portrait of the distant universe, containing 200,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the Big Bang. The tiny, faint, most distant galaxies in the image are similar to the seedling villages from which today’s great galaxy star-cities grew. The faintest and farthest galaxies are just one ten billionth the brightness of what the human eye can see.

The image yields a huge catalog of distant galaxies. “Such exquisite high-resolution measurements of the legacy field catalog of galaxies enable a wide swath of extragalactic study,” says Whitaker, the catalog lead researcher. “Often, these kinds of surveys have yielded unanticipated discoveries that have had the greatest impact on our understanding of galaxy evolution.”

The ambitious endeavor, called the Hubble Legacy Field, also combines observations taken by several Hubble deep-field surveys, including the eXtreme Deep Field (XDF), the deepest view of the universe. The wavelength range stretches from ultraviolet to near-infrared light, capturing all the features of galaxy ‘assembly over time.

“Now that we have gone wider than in previous surveys, we are harvesting many more distant galaxies in the largest such dataset ever produced,” says Garth Illingworth of the University of California, Santa Cruz, and leader of the team. “This one image contains the full history of the growth of galaxies in the universe, from their times as infants to when they grew into fully-fledged ‘adults.’”

Illingworth says he anticipates that the survey will lead to an even more coherent and in-depth understanding of the universe’s evolution in the coming years.

The deep-sky mosaic provides a wide portrait of the distant universe, containing 200,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the Big Bang.

Galaxies trace the expansion of the universe, offering clues to the underlying physics of the cosmos, showing when the chemical elements originated and enabled the conditions that eventually led to the appearance of our solar system and life.

This new wider view contains 100 times as many galaxies as in the previous deep fields. The new portrait, a mosaic of multiple snapshots, covers almost the width of the full Moon, and chronicles the universe’s evolutionary history in one sweeping view. The portrait shows how galaxies change over time, building themselves up to become the giant galaxies seen in the nearby universe. The broad wavelength range covered in the legacy image also shows how galaxy stellar populations look different depending on the color of light.

The legacy field also uncovers a zoo of unusual objects. Many of them are the remnants of galactic “train wrecks,” a time in the early universe when small, young galaxies collided and merged with other galaxies.

Assembling all of the observations was an immense task. The image comprises the collective work of 31 Hubble programs by different teams of astronomers. Hubble has spent more time on this tiny area than on any other region of the sky, totaling more than 250 days.

The image, along with the individual exposures that make up the new view, is available to the worldwide astronomical community through the Mikulski Archive for Space Telescopes (MAST), an online database of astronomical data from Hubble and other NASA missions.

The new set of Hubble images, created from nearly 7,500 individual exposures, is the first in a series of Hubble Legacy Field images. The team is working on a second set of images, totaling more than 5,200 Hubble exposures, in another area of the sky.

In addition, NASA’s upcoming James Webb Space Telescope will allow astronomers to push much deeper into the legacy field to reveal how the infant galaxies actually grew. Webb’s infrared coverage will go beyond the limits of Hubble and Spitzer to help astronomers identify the first galaxies in the universe.

The Hubble Legacy Fields program, supported through AR-13252 and AR-15027, is based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy Inc., under NASA contract NAS 5-26555.

This article first appeared in UConn Today on May 2, 2019.