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.
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, 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.
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.
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
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.
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.
UConn physics professor Nora Berrah has been elected to the historic and prestigious American Academy of Arts and Sciences. This year, more than 200 individuals were elected to the academy with compelling achievements in academia, business, government, and public affairs. Berrah, who was head of the physics department from 2014 to 2018, has been recognized for her distinguished contributions to the field of molecular dynamics, particularly for pioneering non-linear science using X-ray lasers, and spectroscopy using synchrotron light sources.
Using big lasers – like the Linac Coherent Light Source at SLAC National Laboratory on the campus of Stanford University, the most powerful X-ray laser in the world – Berrah’s research explores transformational changes occurring inside molecules when exposed to ultra-intense beams of light. In particular, she investigates physical molecular processes that occur at the femtosecond time scale: one quadrillionth, or one millionth of one billionth, of a second.
“The American Academy for Arts and Science honors excellence and convenes leaders to examine new ideas, and that it is a high honor bestowed on me,” Berrah said.
The 2019 class includes poet and Andrew W. Mellon Foundation president Elizabeth Alexander; chemical and biological engineer Kristi S. Anseth; artist Mark Bradford; gender theorist Judith Butler; economist Xiaohong Chen; academic leader and former Governor Mitchell E. Daniels Jr.; neuro-oncologist Robert B. Darnell; The Atlantic journalist James M. Fallows; author Jonathan Franzen; cell biologist Jennifer Lippincott-Schwartz; data science and McKinsey & Company technology expert James Manyika; former First Lady Michelle Obama; Cisco Systems business leader Charles H. Robbins; mathematician Sylvia Serfaty; philosopher Tommie Shelby; actress and playwright Anna Deavere Smith; and paleoclimatologist Lonnie G. Thompson.
This post has been transcribed from the announcement on UConn Today.
This image is the first ever taken of a black hole, captured by the Event Horizon Telescope (EHT) project. The black center is a direct view of the event horizon of a supermassive black hole with a mass of 6.5 billion times the Sun, lying at the center of the Virgo cluster of galaxies. The bright ring is emission from hot gas just above the event horizon, with an asymmetric shape caused by gravitational lensing of light in the strong gravity of the black hole. The EHT collaboration captured the image using a network of 8 radio telescopes that spanned the Earth, effectively creating a planet-sized interferometer.
This result directly impacts research in galaxy evolution and cosmology that is being carried out at UConn. The following comments from UConn Astrophysics researchers indicate the level of interest that this result has generated within the international Astrophysics community.
This is a stunning technical achievement. Supermassive black holes are the most extreme objects in the Universe, bizarre rips in spacetime that lie in the center of every massive galaxy. But despite their extreme properties, black holes have a remarkably simple mathematical description, with just a few numbers describing all of their vital properties: mass, size, and spin. Until now, the only way to measure black holes was through indirect methods, like my own research program that uses the timing of light echoes in the surrounding gas. The Event Horizon Telescope black hole image is a tremendous first step in a new understanding of extreme gravity and the detailed astrophysics of black holes. – Jonathan Trump, Assistant Professor
I am fascinated by this result and how we can actually see a direct image of a black hole that is a trillion times our distance to the Sun. This is truly an amazing result for human beings achieved within the limitation of our observational instruments. As an observational astronomer who works with black holes, this result also opens up new possibilities to learn about their unknown features such as black hole spin that could revolutionize our understanding of black hole physics. – Yasaman Homayouni, Graduate Student
This result is a beautiful demonstration of what is possible when the global community works in concert towards a scientific goal. Sometimes the greatest discoveries are not found by the biggest new telescopes in space, but through creative thinking, years of dedicated effort, and big data techniques, building upon what we have here on Earth. – Cara Battersby, Assistant Professor
It is truly extraordinary to be able to provide this new evidence for Einstein’s ideas on space and time through observations made no less than one hundred years since he first proposed them. As to the discovery itself, there are two aspects to black holes, one is that they pull everything in, and the other is that they do not let anything out. With nothing being able to get out, they thus look black to an observer on the outside, to thereby give them their black hole name. Now for many years we have had evidence of things falling into black holes, but had never previously had any evidence that things cannot get out. These new data show a fireball ring of things falling in, with the ring surrounding a black space in the center where nothing can get out. We thus confirm that indeed nothing can escape a black hole. – Philip Mannheim, Professor
For more about this topic, see this recent article in the Daily Campus, UConn Astronomy Community Responds Joyously to M87 Black Hole Image.
Step into a fall 2018 class section of PHYS 1602: Fundamentals of Physics II, and you’ll find a scene that’s far from the large introductory science lectures common on most college campuses.
To start, the class of 30 students sits at several triangular workspaces, which today are covered with wires, coils, magnets, and power supplies that the students are using to demonstrate electromagnetic induction. At the start of class, the instructors provided a short lecture before the students set off on their own problem-solving tutorials.
Now, the instructors move from group to group, stopping to answer questions, as students shuttle back and forth to the whiteboards that line the classroom walls.
It’s a scene that’s about to become common in UConn physics courses, thanks to renovations to the Edward V. Gant Science Complex, according to Barrett Wells, professor and head of the Department of Physics.
“We’re rebuilding our classes from the ground up,” he says. “It’s the basis for what we’re going to spread across most of our introductory courses.”
The curricular redesign, says Wells, will replace the typical large-lecture format with smaller classes, utilizing five new studio-style physics learning laboratories to be added to the Gant Science Complex in 2019. These changes will promote active learning, collaborative problem solving, and faculty-student interaction, he says.
“This is a trend we’re seeing in our discipline,” Wells says. “Restricting class size to promote students actively participating during class has been documented to help them achieve and learn more across the board.”
Lecture Meets Lab
Traditional science courses, including those in physics, typically consist of three weekly lectures that hold 100 to 200 students, with once-per-week lab sections where students practice the concepts they learn in lecture.
But this setup poses challenges for professors and teaching assistants to cover the material at the same rate, often causing lecture and lab sections to fall out of synchrony, says Diego Valente, assistant professor in residence of physics and instructor of Fundamentals of Physics II.
In addition, many physics concepts are difficult to teach within the logistical setup of a lecture, and the instructors may have a difficult time knowing whether students comprehend the material, says Valente.
To combat these issues, the Department of Physics piloted redesigned versions of Fundamentals of Physics I and II, the introductory sequence for physics majors, in the spring and fall of 2018, respectively.
The new courses, which will use the physics learning laboratories, merge the lecture and lab sections into three 2-hour class periods per week that hold up to 54 students. Classes are led by the same professor and graduate students.
“[The studio classrooms] allow instructors to interact with students more frequently and discuss concepts with them in depth,” says Valente. “Previously, hands-on group work was limited to lab courses. Now, every single day in class there’s some kind of group activity where students solve problems.”
Lukasz Kuna ’14 (CLAS), ’17 MS, a physics Ph.D. student and teaching assistant for Fundamentals of Physics II, agrees.
“We can present a topic that’s somewhat difficult to understand, and then attack it from all angles,” he says. “It certainly should be the way physics is taught, because it prepares you for more difficult problem solving.”
A Learning Community
The studio learning model also increases the amount of time students spend working collaboratively, says Valente.
Ian Segal-Gould ’21 (CLAS), a physics and mathematics major enrolled in Fundamentals of Physics II, says that the class fosters the collaborative problem-solving that is expected of professional physicists.
“In lecture-based courses, people look at the professor,” he says. “They’re not talking to each other, they’re not solving the problem—they’re looking at somebody else solve the problem. In the real world, physicists work together, so I think the interactive component to this course is on the right track.”
Physics major Megan Sturm ’21 (CLAS) says that working in small groups helps build camaraderie and exposes her to new ideas.
“I know at least half of the class, and it’s way easier to learn that way,” she says. “Someone else will ask a question or say something during the lab that I wouldn’t have even thought about.”
Sturm also says that she enjoys the frequency of interaction with the instructors, noting that Valente circulates through the class, asks students specific questions, and engages in hands-on work with them.
“He’s way more approachable, so when I’m having trouble with things, I don’t have a problem going to office hours,” she says.
Kuna, who has taught for three years in the Department, says that the faculty-student interaction helps him better gauge how students are learning the material.
“Traditionally, if you’re teaching in a large lecture, you somewhat lose the students when they go to lab,” he says. “Here, you get to see where your class stands.”
With a target completion date for phase one renovations set for fall of 2019, the Department is gearing up to redesign other introductory courses, including Physics for Engineers and Physics with Calculus, a general education sequence taken by many pre-med students.
“This is important because we offer courses to majors across the University, and we’re teaching more students each year,” Wells says.
“Our goal is to develop not just comprehension of physical concepts, but also transferable skills–things like communication through group work and computer programming, which students can use in their professional lives,” adds Valente.
He says that these investments in teaching and infrastructure give UConn an advantage in addressing instructional issues common at institutions across the United States.
“This is a really large-scale venture we are doing, something a lot of comparable institutions aren’t able to do,” Valente says. “It shows that UConn is making a big commitment to physics education.”
By: Bri Diaz, College of Liberal Arts and Sciences
This article was originally published in the UConn CLAS Newswletter, November 28 issue
University of Connecticut
College of Liberal Arts and Sciences
Department of Physics
Assistant Professor In-Residence (Storrs Campus)
The Department of Physics at the University of Connecticut invites applications for positions at the rank of Assistant Professor in Residence with an anticipated start date of August 23, 2019. Two positions will be filled at the UConn Storrs campus. The Department of Physics is undergoing a significant change of teaching pedagogy in their introductory course sequences through the implementation of studio-based courses enabled by brand new state-of-the-art teaching facilities. We are pleased to continue these investments by inviting applications for two teaching faculty positions in the Department of Physics.
Applicants are expected to have Ph.D. in physics, astronomy, or a related field; the ability to teach a full range of courses at the undergraduate level and evidence of outstanding teaching. The successful candidates will be expected to share a deep commitment to effective instruction at the undergraduate level and to the mentoring of students in their professional development. Candidates will also share a commitment to the development and innovative improvement of physics courses under the framework of the department’s studio physics project.
The University of Connecticut is committed to building and supporting a multicultural and diverse community of students, faculty, and staff. As an Affirmative Action/Equal Employment Opportunity employer, UConn encourages applications from women, veterans, people with disabilities, and members of traditionally underrepresented populations.
The Physics Nobel prize in 2018 was awarded to Gérard Mourou (École Polytechnique, Université Paris-Saclay), Arthur Ashkin (Bell Laboratories and Lucent Technologies), and Donna Strickland (University of Waterloo) for ground-breaking inventions in the field of laser physics.