Anna Zarra Aldrich, Office of the Vice President for Research (Photo: Trallero Lab/Kansas State Photo)
University of Connecticut physics professor Carlos Trallero has been granted $1.06 million from the Department of Defense, the U.S. Air Force and the Air Force Office of Scientific Research to study recollision physics at the nanoscale to help develop ultrafast electronics.
This research will enhance the knowledge base of electron recollision dynamics at the nanoscale, which can be used to develop ultrafast light-driven electronics. These applications may be made possible by cultivating an improved understanding of the interactions and knowledge of the time scales of light-induced electronic motion including collective plasmonic excitations.
Trallero and co-PIs from Kansas State University will study the response of individual gas-phase nanoparticles to intense femtosecond (10-15 seconds) laser fields using high-harmonics spectroscopy, momentum-resolved photoelectron imaging and corresponding theoretical modeling.
Earlier research on photoelectron emission from dielectric and metal nanoparticles has demonstrated that nanoparticles may be a promising system for exploiting the effects of laser-induced electron recollision due to the interplay between the laser field and the near-field of the particle.
By extending these studies to longer wavelengths (400 to 9000 nanometers) and complementing them with high-harmonic generation from nanoparticles and nanoparticle aggregates, Trallero and his team will help build a better knowledge base of electron recollision dynamics at the nanoscale.
“We predict that through this study, we will identify behaviors on the nanoscale that will differ significantly from those that have been studied at the atomic level,” said Trallero.
The UConn-led team will work on the possibilities of controlling the nanoparticle response, especially plasmonic excitations, by applying synthesized two-color fields. They will also explore harmonic generation from tailor-made nanoparticles as a potential source of intense, short-pulsed XUV light.
By generating harmonics from fractal aggregates and supper-lattices of nanoparticles, Trallero will gather information on the transition from localized molecule-like to de-localized solid-like electron-field interactions. The team also plans to study plasmonic excitations in laser pump, X-ray probe experiments using time-resolved soft X-ray scattering.
In collaboration with ultrafast physics faculty, Professors George Gibson and Nora Berrah, Trallero has started planning and building an “Ultrafast Center,” with ties to industry for research that includes an interdisciplinary group of faculty from the department of physics, the Institute of Materials Science, and the Schools of Engineering and Pharmacy. These faculty are specialized in optics, atomic and molecular physics, condensed matter, material science and engineering.
Carlos Trallero, who received his PhD in physics from Stony Brook University in 2007, joined UConn in 2017. His research focuses on attosecond science, strong field molecular spectroscopy, cohere control, higher-order harmonic generation, non-Gaussian optics, strong field science at long wavelengths and ultrafast optics.
This research is funding under DOD project number FA9550-17-1-0369.
An artist’s rendering of hot material falling into a supermassive black hole, creating what is called the accretion disk, shown in orange. Reverberation mapping measures the time it takes light to travel between two areas of the accretion disk. The ‘light echo’ enables direct measurement of the mass of the black hole. This reverberation mapping project is the first project to weigh many black holes at once. (Image by Nahks Tr’Ehnl, Penn State University)
Surveying millions of astronomical objects, such as supermassive black holes, is a huge and time-consuming undertaking. An international team of researchers, including UConn assistant professor and astronomer Jonathan Trump and graduate student Yasuman Homayouni, have been successful in improving and speeding up this complex task of surveying and mapping our skies, in a study published in the Astrophysical Journal.
“In one sentence, it’s a new, industrial-scale way to weigh large numbers of supermassive black holes,” says Trump.
The effort is part of the Sloan Digital Sky Survey, one of the most successful survey projects in the history of astronomy, which has produced the largest and most detailed three-dimensional maps of the Universe to date. Just like early map makers trying to better understand the planet we live on, modern mapping of galaxies, quasars, and supermassive black holes – the largest type of black hole, found in the center of almost all currently known massive galaxies – gives researchers insight into these phenomena and the Universe we live in. The Sloan Digital Sky Survey is creating as detailed a map as possible of a portion of our sky, and has already collected data on more than three million astronomical objects.
Trump and his colleagues are working toward this goal using a method called reverberation mapping on an especially large sample of distant galaxies with supermassive black holes. The technique measures the mass of the black holes by using light echoes of gas orbiting the black holes, far outside the ‘event horizon’ within which nothing can escape falling into the black hole. With this data, he says, black holes can be described very easily.
“Mass is fundamental,” Trump says. “Once you know the mass, you can calculate almost everything there is to know about a black hole.”
It is this ability to understand so much about black holes from knowing just their mass that makes them good mapping targets. Black holes are more than just rips in space and time, and more than vacuum cleaners sucking up everything that gets too close to their event horizons, Trump explains. There are tight connections between black holes and the galaxies they exist in, so knowing the mass of a black hole allows researchers to unlock more information about the galaxy itself. For example, as black hole mass increases, the galaxy’s mass also increases in lockstep. There is also evidence that black holes act as stabilizing forces within their galaxies, and if a black hole happens to be located close to a supernova, the black hole can act to disperse the heavy elements that are created only in these exploding stars throughout the galaxy.
But there is more to learn. “We know black holes are important and they matter for the rest of the Universe, but we still don’t know exactly why,” says Trump. “They are such strange beasts in our reality.”
Speeding up the Mapping Technique
One drawback of reverberation mapping is that it requires multiple observations, over extended periods of time. With so many astronomical objects to observe and only so much equipment capable of taking such detailed measurements, large-scale mapping of this kind has not previously been possible.
“This technique is hard to do,” says Trump. “You need a lot of very well calibrated observations.”
In addition to the sheer number of objects observed for this project, the light signals observed were at times very faint because their sources of emission are at such great distances.
However, this project’s sizable dataset has increased the sample of black holes with reliably known masses by two-thirds in the past year alone – by 44 quasars to be exact. These data are quickly building on decades of existing work that had around 60 well mapped, representing only the last few percent of the history of the Universe.
The reverberation mapping data have reached deeper, around six or seven billion light years away, looking at more distant black holes. And the future of the project will go even farther, Trump says, which will translate to going even farther back in the history of the Universe.
He draws an analogy to periods in a human life to explain the distances in space and time: “We published data on 44 well-characterized black holes at about the middle age of the Universe. We hope to get to 100 [black holes] at around a quarter of the Universe’s age, so equivalent to around its early adolescence or maybe even childhood. A lot of changes happen in adolescence and childhood for us, and the Universe went through a lot of changes at that age too.”
Muon g-2 Theory Initiative Hadronic Light-by-Light working group workshop
Workshop participants will discuss recent progress and plans to determine the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, which is expected to contribute the largest uncertainty in the Standard Model prediction. The goal of the workshop is to estimate current and expected systematic errors from lattice QCD, dispersive methods, and models and create a plan to address them in time for new experiments at Fermilab and J-PARC. For more information, please visit the workshop web site.
December 19, 2017 – Colin Poitras – UConn Communications
Scientists from three major research universities successfully manipulated the outcome of a chemical reaction and, in doing so, created a rare molecular ion.
Through a process known as “controlling chemistry,” the researchers bonded an oxygen atom to two different metal atoms, creating the barium-oxygen-calcium molecular ion or BaOCa+ The same process could lead to the creation of other exotic new materials and the design of novel chemical compounds, according to the team from the University of Connecticut, University of California-Los Angeles, and University of Missouri, whose work appeared in the Sept. 29 online issue of Science.
“It’s doing chemistry with the tools of physics,” says Robin Côté, UConn physics professor and associate dean for physical sciences who co-authored the study. Côté is a leading theorist in the field of ultracold molecular ion reactions.
“Usually in chemistry you can’t see molecules react,” says Côté. “You do experiments and you get a reaction with a range of products, which can be analyzed with mass spectrometry and other tools. What our team did allowed us to image ions directly to get a much clearer picture of what is happening within the chemical reaction itself. We were able to prepare a system in an ultracold environment that was very pristine and that allowed us to see exactly how the molecules and atoms were behaving.”
Watch an animation of barium ions inside a Paul Trap.
Previous work had observed hypermetallic alkaline earth oxides consisting of an oxygen atom sandwiched between two identical alkaline earth atoms, such as barium or calcium.
But for the first time in this study, researchers observed compounds consisting of an oxygen atom bonded to two different metal atoms. Such compounds are believed to have unique properties resulting from the broken symmetry.
It’s nice to see that a phenomenon you envisioned at one time as too difficult to do, is indeed possible.— Robin Côté
The researchers used a host of equipment to accomplish the breakthrough – quantum chemistry computations, lasers, a hybrid ultracold atom-ion trap, and something called a “radially-coupled time-of-fight mass spectrometer.”
By trapping atoms and ions in an ultracold hybrid magneto-optical trap and then cooling them down to a temperature one one-thousandth degree above absolute zero, the scientists were able to observe a reaction between atoms and molecules that hadn’t been seen before.
See a real time image of crystal ions.
They used lasers to manipulate calcium atoms into a specific quantum state, which allowed the chemical reaction to proceed and the new molecules to form when they normally shouldn’t. To confirm their results, the researchers released the ions and molecules from their ultracold suspension, where they would then “fly” into the mass spectrometer to be analyzed and measured further.
The process could serve as a platform for gaining greater insight into chemical reaction dynamics. Armed with such knowledge, chemists and physicists could engineer specific chemical reactions and synthesize new products currently unavailable to us, such as more advanced chemical sensors, quantum computer processors, and medications with fewer side effects.
Joining Côté on the project were UConn research professor John Montgomery Jr., an expert in computational quantum chemistry, and postdoctoral researcher Ionel Simbotin. UCLA physics professor Eric Hudson, an expert in hybrid atom-ion trapping, served as the project’s principal investigator; and UCLA graduate students Prateek Puri (lead author) and Michael Mills, together with postdoctoral researcher Christian Schneider, performed the measurements. University of Missouri chemistry professor Arthur Suits rounded out the team.
Côté was the first to propose studying ultracold atom-ion systems in 2000, shortly after arriving at UConn. And, UConn physics professor emeritus Winthrop Smith, in 2001, was the first to propose using a hybrid ultracold ion-atom trap to conduct the observations in order to learn more about the fundamental processes of chemical reactions.
Experimental and theoretical physicists and chemists have been working in the field ever since. Lately, new advances in technology, such as the hybrid trap used in this study, are providing scientists the tools they need to progress.
To some extent, the study confirmed Côté’s and Smith’s proposal that hybrid atom-ion traps could be valuable tools for exploring the fundamental dynamics underlying chemical reactions.
“It’s nice to see that a phenomenon you envisioned at one time as too difficult to do, is indeed possible,” says Côté. “We did calculations showing this behavior should take place, and it is great to see that now confirmed in the lab.”
In the current study, the researchers spent more than 18 months trying to figure out what was driving the chemical reaction creating the new molecule. They analyzed experimental data, performed quantum chemistry calculations, and tested various theories in the lab. In many ways, it was like solving a mystery. The scientists knew the molecule could be formed because their UCLA peers had seen them in the hybrid ion trap. The challenge was trying to explain how it was happening.
The team ultimately determined the precise mechanisms that allowed the mixed hypermetallic earth oxide to form, which involved the amount of energy expended in the reaction and a certain spin of electrons.
“Most chemical reactions take place in the ground state, which is to say, a system’s lowest-energy state,” says Montgomery. “The use of quantum chemical calculations enabled us to understand that this particular reaction could only take place on the excited triplet state, which is a higher-energy state. This was then verified by experiments.”
That kind of precise knowledge of what exactly is occurring during a chemical reaction goes to the very core of controlling chemistry.
“When something reacts in chemistry, you can compute the outcome or products, but you can rarely control the process,” says Côté. “But if you are able to know exactly what is happening in that reaction, what components are rotating, what is spinning, what’s vibrating with this energy or that energy, and if you’re able to control those quantities, then it is feasible to design a reaction or a device to ensure a particular outcome most of the time.”
The research was funded by the National Science Foundation (PHY-1205311, PHY-1415560, and DGE-1650604) and Army Research Office (W911NF-15-1-0121, W911NF-14-1-0378, and W911NF-13-1-0213).
UConn is one of seven universities working in this area under a multimillion-dollar research grant awarded by the Department of Defense. The MURI award, which stands for Multidisciplinary University Research Initiative, also includes researchers from the physics departments at UCLA, Northwestern, and Temple, and from the chemistry departments at Georgia Tech, Emory, and Missouri.
UConn on the Front Line to Glimpse Farthest Reaches of Universe
November 27, 2017 – Elaina Hancock – UConn Communications
Two UConn physics professors will be among the world’s first scientists to explore the universe using the new James Webb Space Telescope when it is launched in 2019. The telescope, shown here at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is designed to be a large space-based observatory optimized for infrared wavelengths, and will be the successor to the Hubble Space Telescope and the Spitzer Space Telescope. (Photo by Alex Wong/Getty Images)
Two UConn physics professors will be among the world’s first scientists to explore the universe using the new James Webb Space Telescope, as announced earlier this month by the National Aeronautics and Space Administration.
[The] James Webb [Space Telescope] will begin teaching us entirely new things … things we don’t even know about. — Jonathan Trump
Just like the highly anticipated release of a new phone, game, or gadget, astrophysicists worldwide are eager to start using the new telescope, the latest technology for viewing distant elements of our universe, which is currently set to launch in 2019. But rather than stand in line for hours outside a store, researchers had to submit compelling proposals to secure their spot in line and an opportunity to use the new technology.
The highly competitive, peer-reviewed James Webb Space Telescope Early Release Scienceprogram was created to test the capabilities of the new observatory and to showcase the tools the telescope is equipped with. Of more than 100 proposals submitted, only 13 were chosen to participate in the early release phase, including two separate proposals involving UConn researchers Kate Whitaker and Jonathan Trump, both assistant professors of physics.
Full-resolution mosaic of the CANDELS/EGS field, the survey field for the CEERS proposal’s research. (Anton M. Koekemoer/Space Telescope Science Institute)
Passing the Telescope Torch
The James Webb Space Telescope, designed to be a large space-based observatory optimized for infrared wavelengths, will be the successor to the Hubble Space Telescope. The Hubble telescope has been a versatile workhorse and vital tool since its launch in 1990, allowing researchers to peer deep into space and get crisp glimpses of distant galaxies.
But it has technological limitations, and is not currently scheduled for any upgrades or servicing. Since its last service in 2009, Whitaker says, many researchers have been keeping their fingers crossed that it would continue functioning. Hubble is currently the only way to make observations that are required for the type of research she and many others conduct.
“A lot of my research right now is pushing Hubble to its limits,” she notes. “It’s an exciting time, because with the capabilities of the James Webb Space Telescope, we will really push into the frontiers of research.”
The Hubble (top left) and James Webb Space Telescope (top right). The middle portion of the image shows the relative location of the telescopes to Earth and the moon; Webb will launch much further into space. At the bottom of the image, the spectrum of light observed by both Hubble and Webb is shown, with Webb’s capabilities stretching farther into the infrared range, well past Hubble’s capabilities. (Slide from the Hubble 25th anniversary website, hubble25th.org)
The James Webb Space telescope is equipped with tools that will surpass Hubble’s capabilities. Webb will be launched further into space and will be capable of powerful imaging that will produce sharper images and be able to capture images into the infrared range.
Peering into the infrared range allows researchers to observe signatures, in the form of light, from events that happened long ago. The universe is constantly expanding and as light travels, it gets stretched over time, Whitaker explains. The further back you go, say a few billion years or so, the light is stretched so much that it will shift from the visible region of the spectrum into the infra-red.
Cutting-Edge Research, Winning Proposals
Whitaker is a science collaborator on a proposal titled “TEMPLATES: Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star formation,” exploring star formation in galaxies at a distance of around 10 billion years in the past, something impossible to observe until the high resolution of the new telescope. They hope to more closely study characteristics of those distant galaxies that have until now, only been discernible in more local galaxies.
“Since we cannot travel to these distant galaxies, all we can do is sit here and wait for their light to reach our telescopes,” says Whitaker.
Trump is a co-investigator on the proposal called “CEERS: The Cosmic Evolution Early Release Science Survey,” a plan to conduct an extragalactic survey in hopes of gaining insights into the formation of the first galaxies following the big bang. They plan to look at aspects of the assembly of galaxies, including their number density, chemical abundance, star formation, and the growth of supermassive black holes.
“Hubble has totally transformed our view of the universe and James Webb will begin teaching us entirely new things,” Trump says. “I’m incredibly excited to think about all of the things we don’t even know about, that James Webb will begin to tell us.”
The Early Release Program is aimed not only to showcase the capabilities of the James Webb Space Telescope right away, but to make the data publicly available as soon as possible. It is anticipated that the data will facilitate huge breakthroughs in research.
Stay tuned: 2019 promises to be an exciting year in astrophysics.
The physics department will be hosting Prof. Geri Richmond from the University of Oregon to give a Special Lecture on Diversity and Inclusion. The talk is Tuesday, November 28, 3:30pm, Physics/Biology Building, Room 131
The American Physical Society (APS) has named two UConn Physics faculty as APS Fellows. APS Fellowship is a distinct honor signifying recognition by one’s professional peers and is an honor bestowed by election. The criterion for election is exceptional contributions to the physics enterprise; e.g., outstanding physics research, important applications of physics, leadership in or service to physics, or significant contributions to physics education.
In 2017, Susanne Yelin and Alex Kovner are named Fellows of the American Physical Society.
APS Fellow Susanne Yelin: For pioneering theoretical work with quantum coherences, such as near-resonant nonlinear quantum optics, for work with hybrid systems, such as molecular and solid state materials, and for work with many-body and cooperative systems and super-radiance.
APS Fellow Alex Kovner: “ For ground-breaking contributions to the physics of strong interactions in high energy hadronic and nuclear collisions, including high parton densities and gluon saturation.”
The UConn Physics Graduate Student Association sponsored a social event featuring UConn dairy bar ice cream to welcome back students after the summer break. Other regular events throughout the year sponsored by the PGSA include the Holiday Party in December, the Poster Exhibition Competition in April, and the Department Picnic in May.
The Physics Department has recently expanded its research and teaching specialties to include Astronomy with the addition of three new junior faculty: Cara Battersby, Jonathan Trump, and Kate Whitaker. In addition to the expertise in Observational Astronomy using the latest instruments and techniques, they are also spearheading a suite of new courses in Astronomy and Astrophysics. Following on with the popularity of these course with our students, we have now introduced a new minor in Astronomy to give undergraduate majors across a broad range of majors the opportunity to make Astronomy a prominent part of their studies.
Students in PHYS 1601q, taught by Professor Jason Hancock, work during a lab that observes how an external mass can affect oscillation by producing torque. They use a device called an ioLab to record data, and use the data in a program called Mathematica for analysis. The lab was in the Edward V. Gant science complex on April 20, 2018. (Garrett Spahn/UConn Photo)
Following up on results from Physics education research conducted at MIT and elsewhere, professor Jason Hancock has begun the process of transforming the way Introductory Physics is taught at the University of Connecticut. Starting with the course PHYS 1601Q for physics majors, Prof. Hancock has developed a curriculum that integrates aspects of both lecture and lab components in an active learning environment that introduces students to all of the essential physics covered in the traditional lecture course, but in a format where students work in groups and discover the principles of classical mechanics for themselves using a hands-on approach. Experience gained with PHYS 1601Q will lay the ground work for the eventual conversion of the full suite of calculus-based Introductory Physics courses into an active learning format.
Reload document 
Open in new tab 
