Events List for the Academic Year
Event Time:
Thursday, January 30, 2025 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar
2025-01-30T10:00:00
2025-01-30T11:00:00
Connected Network Model for the Mechanical Loss of Amorphous Materials
Event Information:
For over 50 years, the two-level system (TLS) model has stood as the prevailing description of thermal and acoustic properties of amorphous solids. Atomistic modeling shows that TLS are not independent as typically assumed, but form a sparse, interconnected network. I will discuss the mechanical loss in amorphous solids based on the nonequilibrium thermodynamics of connected networks, providing a major advance beyond the quintessential two-level system model, and revealing new avenues for the study amorphous materials. Amorphous mirror coatings with exceptionally low mechanical loss are critical components in the next generation of gravitational wave detectors. I will also briefly discuss how these results could impact the TLS model for dielectric loss in superconducting qubits.
Event Location:
BRIM 311
Event Time:
Thursday, January 30, 2025 | 9:00 am - 12:00 pm
Event Location:
Room 288 of the Stewart Blusson Quantum Matter Institute (QMI) building (2355 East Mall)
Add to Calendar
2025-01-30T09:00:00
2025-01-30T12:00:00
Decoupled Magnetic Centers in Anion-substituted Nickel Oxide
Event Information:
Abstract:
The central focus of this dissertation is the study of crystal systems whose properties are significantly influenced by their transition metal components. Each project follows a systematic approach: we synthesize crystal systems using the molecular beam epitaxy thin film growth technique, characterize these materials through high-resolution spectroscopy measurements---both in-house and using synchrotron radiation---and interpret the underlying physics by comparing our findings with theoretical models.
First, we offer an in-depth study of N substitution in NiO. NiO is regarded as a prototypical strongly correlated material, often serving as a model system for understanding electron-electron interactions. This makes NiO an ideal candidate for our study of individual centers in antiferromagnetic strongly correlated oxides. These centers are imperfections in a crystal lattice that host localized electronic states and magnetic properties, distinct from the surrounding crystal. With the growing interest in quantum technologies, significant efforts have been made to extend individual centers to a wide array of materials. Here, we explore the formation of Ni-N-Ni units upon introducing low concentrations of N into the NiO lattice. These units exhibit properties essential for quantum devices: they are decoupled from the rest of the crystal and possess degenerate quantum states that could be perturbed by external magnetic fields or finite temperatures.
We then study the electronic structures of various Ni-based compounds, namely NiO, N-substituted NiO, and Ca-substituted LaNiO3. We analyze how these structures differ from other systems and their unsubstituted counterparts. In N-substituted NiO, we further investigate its electronic structure through core-level photoemission spectroscopy, examining doping and temperature dependence to deepen our understanding of non-local screening in this material.
Finally, we investigate Ti thin films and their interaction with polar surfaces. Polar materials are characterized by alternating electronically charged layers, leading to surface instabilities that can increase interfacial interactions. We present an experimental technique to stabilize polar MgO (111) and study its impact on the superconducting properties of Ti thin films deposited on this substrate.
Event Location:
Room 288 of the Stewart Blusson Quantum Matter Institute (QMI) building (2355 East Mall)
Event Time:
Tuesday, January 28, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
Add to Calendar
2025-01-28T16:00:00
2025-01-28T17:00:00
The Black Hole Information Paradox: a resolution on the horizon?
Event Information:
Welcome to the fourth talk in our new Pioneers in Theoretical Physics Colloqium Series.
On January 28th, we present Dr. Netta Engelhardt, professor of physics at the Massachusetts Institute of Technology.
Abstract:
Can quantum information escape from a black hole? General relativity and quantum mechanics, which govern the behavior of black holes and quantum information, respectively, do not agree on the answer. This disagreement is the essence of the famous nearly 50 year old Black Hole Information Paradox. Understanding the resolution of this problem is a central pillar in the quest for quantum gravity. Recently there has been an unprecedented amount of progress towards a resolution. I will describe the origin of the paradox, the current status in light of the new developments, and resulting new insights into high energy gravitational phenomena.
Bio:
Netta Engelhardt grew up in Jerusalem, Israel and Boston , MA. She received her BSc in physics and mathematics from Brandeis University and her PhD in physics from the University of California, Santa Barbara. She was a postdoctoral fellow at Princeton University and a member of the Princeton Gravity Initiative prior to joining the physics faculty at MIT in July, 2019.
She works on quantum gravity, primarily within the framework of the AdS/CFT correspondence. Her research focuses on understanding the dynamics of black holes in quantum gravity, leveraging insights from the interplay between gravity and quantum information via holography. Her current primary interests revolve around the black hole information paradox, the thermodynamic behaviour of black holes, and the cosmic censorship hypothesis (which conjectures that singularities are always hidden behind event horizons).
Learn More:
See her MIT faculty page: Netta Engelhardt » MIT Physics
See her wikipedia page: Netta Engelhardt - Wikipedia
See this article on a brief introduction to the AdS/CFT correspondence: lezionilosanna.pdf
Black holes in the quantum realm: Extending classical black hole inequalities into the quantum realm
More about the Black Hole paradox: Black hole paradox that stumped Stephen Hawking may have a solution, new paper claims | Live Science
Event Location:
HENN 201
Event Time:
Monday, January 27, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar
2025-01-27T16:00:00
2025-01-27T17:00:00
Bridging the Gap: Linking Disk Observations to Exoplanet Demographics
Event Information:
Abstract:
How did our Solar System and other planetary systems form? Which systems are most likely to host habitable worlds? These are critical questions as we plan for missions capable of detecting Earth analogues and search for atmospheric signatures of life. I will discuss how linking multi-wavelength observations of disks around young stars and exoplanet demographics shed light on these questions. First, I will present evidence for a dominant mechanism to form giant planets. Next, I will summarize an ongoing effort to constrain how the most common planets, sub-Neptunes and super-Earths, form and evolve. I will conclude by discussing how upcoming facilities will further these studies and their role in reconstructing the paths to habitable worlds.
Bio:
My research is directed towards understanding how planets form and evolve and how common are planetary systems like our own Solar system. To this end, my group carries out observations aimed at characterizing the physical and chemical evolution of gaseous dust disks around young stars, the birth sites of planets. In addition, we use exoplanet surveys to re-construct the intrinsic frequency of planets around mature stars. By linking the birth sites of planets to the exoplanet populations, we contribute to building a comprehensive and predictive planet formation theory, a necessary step in identifying which nearby stars most likely host a habitable planet like Earth.
Learn More:
See her personal website here: http://ilariapascucci.com/
View her faculty webpage here: https://www.lpl.arizona.edu/faculty/ilaria-pascucci
Learn more about planetary systems projects from NASA: https://science.gsfc.nasa.gov/solarsystem/planetarysystems/projects
Check out the NASA exoplanet archive: https://exoplanetarchive.ipac.caltech.edu/docs/counts_detail.html
Event Location:
HENN 318
Event Time:
Friday, January 24, 2025 | 5:30 pm - 8:30 pm
Event Location:
Hebb Building 2045 East Mall, Vancouver, BC V6T 1Z1. Meet on the ground floor (use entrance from Volkoff Lane)
Add to Calendar
2025-01-24T17:30:00
2025-01-24T20:30:00
2025 Planetary Parade! See Mars, Jupiter, Saturn and Venus!
Event Information:
2025 Planetary Parade!
The UBC Department of Physics and Astronomy and the UBC Astro Club will be hosting an observing event on the roof of the UBC Hebb building on Friday 24 January, 2025.
This is your chance to see Mars, Jupiter, Saturn and Venus with our telescopes! The weather forecast is great - it is a perfect opportunity to view these beautiful planets.
Meet us at the ground floor of Hebb building, using the entrance from Volkoff Lane (see map below). Doors will open at 5:30pm, and the observing party starts at 6pm.
Event Location:
Hebb Building 2045 East Mall, Vancouver, BC V6T 1Z1. Meet on the ground floor (use entrance from Volkoff Lane)
Event Time:
Thursday, January 23, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
Add to Calendar
2025-01-23T16:00:00
2025-01-23T17:00:00
New frontiers in transient astrophysics: gravitational-wave multi-messenger sources and r-process nucleosynthesis
Event Information:
Abstract:
The detection of GW170817 enabled us to track down and watch the cataclysmic event in multiple wavelengths of light, allowing us to scrutinize the source of these cosmic ripples for the first time. This discovery provided the first solid evidence that neutron-star smashups are the source of much of the Universe's gold, platinum and other heavy elements in the Universe. With a single event, we were able to answer fundamental questions in general relativity, cosmology, nuclear physics, and astrophysics. However, other parts of the story told by these events are still shrouded in mystery. For astronomers and physicists across disciplines, this is an extremely exciting time to be alive.
Bio:
Ramirez-Ruiz was born in Mexico, studied physics at the Universidad Nacional Autónoma de México, and pursued his PhD at Cambridge University. He was the John Bahcall Fellow at the Institute for Advanced Study at Princeton before joining the faculty at UCSC, where he is a professor of astrophysics and astronomy and holds the Vera Rubin Presidential Chair.
Since joining the UCSC faculty in 2007, Ramirez-Ruiz has won a number of awards for his research, including a Packard Fellowship, the NSF CAREER Award, the Radcliffe Fellowship at Harvard, the Niels Bohr Professorship from the Danish National Research Foundation, the Presidential Award for Excellence in Science Mathematics and Engineering Mentoring, the HEAD Mid-Career Prize from the AAS and the Bouchet Award and the Dwight Nicholson Medal from the American Physical Society. He is a fellow of the American Physical Society and member of the Mexican Academy of Sciences and the American Academy of Arts and Sciences.
Learn More:
What is GW (Gravitational Wave) #170817?: GW170817 - Wikipedia
More about this neutron star smashup: Neutron star smashup seen for first time, 'transforms' understanding of Universe and Dawn of an Era: Astronomers Hear and See Cosmic Collision | Discover Magazine
What does a binary star-merger look like? ESA - Neutron star merger
Event Location:
HENN 201
Event Time:
Thursday, January 23, 2025 | 3:00 pm - 4:00 pm
Event Location:
Outside of HENN 200 (atrium)
Add to Calendar
2025-01-23T15:00:00
2025-01-23T16:00:00
PHAS Thursday Tea!
Event Information:
We welcome you to our weekly PHAS THURSDAY Tea!
Term 2 has delivered a new schedule for our friendly neighbourhood tea event: join us Thursdays from 3-4pm in the atrium outside of HENN 200. For those interested, we invite you to follow up with our weekly Department colloquia in HENN 201 from 4-5pm.
We welcome all students, staff and faculty to meet new-to-you colleagues, catch up with your physics community and to learn about current happenings in the PHAS Department.
Meet your hosts from the EDI Community Building Working Group:
Jess McIver
Adele Ruosi
Megan Bingham
Evan Goetz
Mona Berciu
Howard Li
Mandana Amiri
We look forward to meeting you!
Event Location:
Outside of HENN 200 (atrium)
Event Time:
Thursday, January 23, 2025 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar
2025-01-23T10:00:00
2025-01-23T11:00:00
Just-in-time compiling Shor's algorithm with PennyLane and Catalyst
Event Information:
As quantum computing hardware continues to improve, so must the tools we use to write quantum algorithms. There is a growing need for more expressive quantum programming languages that enable developers to write code at higher levels of abstraction than quantum circuits. This, in turn, necessitates robust and automated compilers that can generate optimized sequences of quantum operations in a scalable way. Such compilers are especially important for algorithms with many interdependent classical and quantum subroutines, such as Shor's factoring algorithm. In this talk I will provide a pedagogical introduction to Shor's algorithm by presenting its implementation at varying levels of abstraction. While its high-level subroutines are straightforward to express, compilation and optimization incurs a large overhead due to the algorithm's randomized nature. To that end, I will highlight ongoing work on a fully just-in-time-compiled implementation using PennyLane and Catalyst. I'll discuss its scaling, practical resource requirements, implementation tricks (and unique quirks), and the feasibility of executing it on near-term hardware.
Event Location:
BRIM 311
Event Time:
Wednesday, January 22, 2025 | 4:30 pm - 6:00 pm
Event Location:
Frederic Wood Theatre - UBC-V campus (6354 Crescent Rd, Vancouver, BC V6T 1Z2)
Add to Calendar
2025-01-22T16:30:00
2025-01-22T18:00:00
Outer Space Institute: John S. MacDonald Outer Space Lecture
Event Information:
The Outer Space Institute's upcoming John S. MacDonald Outer Space Lecture will be on January 22, 2025 at the Frederic Wood Theatre on UBC campus from 4:30-6:00 pm.
The talk will feature Marc Garneau, Canadian astronaut and former Minister of Foreign Affairs and Dumitru Dorin Prunariu, Romanian cosmonaut and former Chairman of the UN Committee on the Peaceful Uses of Outer Space!
Admission is FREE! Space is limited however so we ask that people register ahead of time.
More info can be found on our website here: https://outerspaceinstitute.ca/event/3rd-annual-john-s-macdonald-outer-space-lecture/
Or on the Eventbrite registration page: https://www.eventbrite.ca/e/3rd-annual-john-s-macdonald-outer-space-lecture-tickets-1141274916999?aff=oddtdtcreator
Event Location:
Frederic Wood Theatre - UBC-V campus (6354 Crescent Rd, Vancouver, BC V6T 1Z2)
Event Time:
Monday, January 20, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar
2025-01-20T16:00:00
2025-01-20T17:00:00
SPHEREx: An All-sky Infrared Spectral Survey Explorer Satellite
Event Information:
Abstract:
SPHEREx, a mission in NASA's Medium Explorer (MIDEX) program, is an all-sky survey satellite designed to address three science goals with a single instrument, a wide-field spectral imager. SPHEREx will probe the physics of inflation through measurements of non-Gaussianity by studying large-scale structure, surveying a large cosmological volume at low redshifts, complementing high-z surveys optimized to constrain dark energy. The origin of water and biogenic molecules will be investigated in all phases of planetary system formation - from molecular clouds to young stellar systems with protoplanetary disks - by measuring ice absorption spectra. We will chart the origin and history of galaxy formation by mapping large-scale spatial power in two deep fields located near the ecliptic poles. Following in the tradition of all-sky missions, SPHEREx will be the first all-sky near-infrared spectral survey, creating spectra (0.75 – 4.2 um at R = 40, and 4.2 – 5 um at R = 135) with high sensitivity using a cooled telescope with a wide field-of-view for large mapping speed. During its two-year mission, planned to begin in early 2025, SPHEREx will produce four complete all-sky maps that will serve as a rich archive for the astronomy community. With over a billion detected galaxies, hundreds of millions of high-quality stellar and galactic spectra, and over a million ice absorption spectra, the archive will enable diverse scientific investigations including studies of young stellar systems, brown dwarfs, high-redshift quasars, galaxy clusters, the interstellar medium, asteroids and comets.
Bio:
Prof. Bock came to cosmology only at the end of his PhD. At Berkeley, he wrote his thesis on sounding rocket observations of carbon emission in the diffuse interstellar medium (ISM), where he also helped develop the instruments used to make these observations. While he was writing his thesis, physicists Prof. Paul Richards and Prof. Andrew Lange were studying the anisotropy of the cosmic microwave background (CMB) with competing balloon missions, hoping to measure the geometry of the universe. “To distract me from that task (thesis writing)” Bock says, “I got involved in developing detectors for BOOMERanG” (Prof. Lange’s experiment). These new bolometers (which could be made incredibly sensitive) also ended up on Prof. Richards’s MAXIMA experiment. Eventually, both missions were smashing successes, and both found evidence for a flat universe! Bolometers like these continued to be critical for experimental cosmology missions, such as the Planck satellite and Prof. Bock’s more recent experiments like BICEP, now focusing on measuring the polarization of the CMB. [from Astrobites]
Learn More:
View his personal website here: https://pma.caltech.edu/people/james-j-jamie-bock
See his research website here: https://cosmology.caltech.edu/
Read up on the SPHEREx project and team: https://science.jpl.nasa.gov/projects/spherex/
SPHEREx goals: https://ui.adsabs.harvard.edu/abs/2018AAS...23135425L/abstract
SPHEREx news and updates: https://spherex.caltech.edu/news/spherex-submitted-as-a-nasa-medium-class-explorer
Event Location:
HENN 318
Event Time:
Thursday, January 16, 2025 | 5:00 pm - 6:30 pm
Event Location:
Coach House, Green College (6201 Cecil Green Park Road, Vancouver, BC / V6T 1Z1 Canada)
Add to Calendar
2025-01-16T17:00:00
2025-01-16T18:30:00
Emeritus College Series: Astrophysics Over Time
Event Information:
ASTROPHYSICS OVER TIME Speakers: William H. McCutcheon, Professor Emeritus, Physics and Astronomy; Jess McIver, Associate Professor, Physics and Astronomy; and Pedro Villalba González, PhD Candidate, Physics and Astronomy, and Green College Resident Member.Location: Coach House, Green College, UBC Date/Time: Thursday, January 16, 5-6:30 pm, with reception to follow
Abstract:
This series, co-hosted with UBC Emeritus College, brings together scholars who inhabit the same academic discipline or field of study, and are at different stages of their careers, to talk about how the boundaries separating their field of specialization from other fields have shifted over time. This third event in the series will stage a conversation between scholars of Astrophysics. The moderator will ask the panelists a series of questions about their perspectives on the discipline, and the discussion will be opened at an early stage to members of the audience. The goal of the event is to grasp the interdisciplinary nexus that is "Astrophysics" in Canadian and other universities and to peer into possible futures of the field.
Event Location:
Coach House, Green College (6201 Cecil Green Park Road, Vancouver, BC / V6T 1Z1 Canada)
Event Time:
Thursday, January 16, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
Add to Calendar
2025-01-16T16:00:00
2025-01-16T17:00:00
Dynamics of active bio-inspired materials: from cytoskeleton composites to circadian colloids
Event Information:
Abstract:Active dynamics and out-of-equilibrium reconfigurability, at the heart of diverse biological processes, are widely studied across disciplines in efforts to infuse such properties into next-generation autonomous materials, and to understand the physics underlying living systems that are far from equilibrium. In this talk, I will discuss two orthogonal paths we take, inspired by biology, to introduce active dynamics, restructuring and non-equilibrium rheological properties into soft matter systems. Our work on motor-driven composites of actin filaments and microtubules reveal that synergistic interactions between these two polymers confers emergent strength and reversibility into composites; while competition between their associated molecular motors, myosin and kinesin, gates composite restructuring and suppresses de-mixing and advection. In a very different approach to active matter design, we harness functionalized circadian clock proteins to drive oscillatory self-assembly of diffuse colloids into percolated networks of colloidal superstructures on a timescale programmed by the circadian rhythm. Throughout the talk, I will also highlight methods our lab has developed to study these systems, including advanced optical tweezers microrheology and differential dynamic microscopy.
Bio:
Robertson-Anderson is Associate Provost for Engaged Scholarship at University of San Diego, where she has been a Professor of Physics and Biophysics since 2009.
Robertson-Anderson received her BS in Physics from Georgetown University in 2003, funded by a Clare Boothe Luce Scholarship. She earned her PhD in Physics from University of California, San Diego in 2007, funded by an NSF Graduate Research Fellowship, after which she was awarded an NIH fellowship to pursue a molecular biology postdoc at The Scripps Research Institute.
Robertson-Anderson joined the faculty at University of San Diego with the goal of engaging undergraduates in cutting-edge research and shaping undergraduate physics programs and research at a national level. She served as department Chair for 8 years, overhauling the physics curriculum and research culture, and establishing an interdisciplinary Biophysics BS that has served as a model for liberal arts institutions nationally.
Robertson-Anderson’s research program aims to elucidate microscale mechanics and macromolecular transport in bio-inspired soft and active matter systems. Her lab has pioneered novel optical tweezers microrheology and fluorescence microscopy techniques to probe these systems across decades of spatiotemporal scales. She is also a leading expert in engineering biopolymer networks that leverage biological design paradigms to solve problems in soft and active matter physics.
Robertson-Anderson has been awarded over $5M to fund her research program, including a Keck Foundation Research Grant, NSF DMREF Award, NSF CAREER Award, and Air Force Young Investigator Award. In 2022, she was awarded a Research Corporation Cottrell Scholars STAR Award for her excellence in research and teaching, and in 2023 she was awarded the APS Prize for Faculty research at an undergraduate institution and was named an APS Fellow.
Learn More:
Read her biography here: https://www.sandiego.edu/provost/office/biography.php?profile_id=399
See her appointment as Associate Provost for Engaged Scholarship: https://www.sandiego.edu/provost/office/biography.php?profile_id=399
Read about the Robertson-Anderson lab, "Bio-inspired squishy physics and optical trapping": https://www.biospotlab.com/
Event Location:
HENN 201
Event Time:
Thursday, January 16, 2025 | 3:00 pm - 4:00 pm
Event Location:
Outside of HENN 200 (atrium)
Add to Calendar
2025-01-16T15:00:00
2025-01-16T16:00:00
PHAS Thursday Tea!
Event Information:
We welcome you to our weekly PHAS THURSDAY Tea!
Term 2 has delivered a new schedule for our friendly neighbourhood tea event: join us Thursdays from 3-4pm in the atrium outside of HENN 200. For those interested, we invite you to follow up with our weekly Department colloquia in HENN 201 from 4-5pm.
We welcome all students, staff and faculty to meet new-to-you colleagues, catch up with your physics community and to learn about current happenings in the PHAS Department.
Meet your hosts from the EDI Community Building Working Group:
Jess McIver
Adele Ruosi
Megan Bingham
Evan Goetz
Mona Berciu
Howard Li
Mandana Amiri
We look forward to meeting you!
Event Location:
Outside of HENN 200 (atrium)
Event Time:
Thursday, January 16, 2025 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar
2025-01-16T10:00:00
2025-01-16T11:00:00
A Personal Journey from a Condensed-Matter Theorist to an Education Researcher and Practitioner: Lessons Learned
Event Information:
Trained as a condensed-matter theorist at UBC under Mona Berciu, over the past five years I have become increasingly involved in education research and practice. In fact, I've become quite an active leader in developing and promoting Meaningful Learning towards Advanced Knowledge Generators for Cultivating Creators (ML4C). In this talk, I will share the key ideas and concepts of ML4C, which are summarized in the next paragraph. I hope that in the future, some of the courses at UBC will also be taught in this way, and that the whole curriculum—even the entire program—can be redesigned according to the core ideas of ML4C. Besides the ideas and concepts, you may also see how they were developed starting from personal learning and research experiences. In fact, this process itself is an example of how advanced knowledge generators help create knowledge, although this time on teaching and learning. ML4C provides answers to the following questions: -What to teach: Advanced Knowledge Generators (AKG), such as the ways of thinking and the methods of analysis of a discipline. -How to teach: By experiencing knowledge creation. -Why teach them in this way: One needs advanced knowledge generators to be a creator, and one masters advanced knowledge generators better by experiencing them in use. -Meaningful: For me, being a teacher who can help others become creators is satisfying, while being a teacher who feeds factual, procedural, or even conceptual knowledge to students is not.
Event Location:
BRIM 311
Event Time:
Tuesday, January 14, 2025 | 9:00 am - 11:00 am
Event Location:
HENN 309
Add to Calendar
2025-01-14T09:00:00
2025-01-14T11:00:00
Studies of Ultracold Neutron Dynamics and Systematic Effects for the TUCAN EDM Experiment
Event Information:
Abstract:
The TRIUMF Ultracold Advanced Neutron (TUCAN) Collaboration is developing a new measurement of the neutron electric dipole moment (nEDM) with the goal of improving the current best limit of dn < 1.8E-26 ecm (90% C.L.) to the level of dn < 2E-27 ecm (90% C.L.). A non-zero nEDM requires the violation of charge-parity (CP) symmetry, and so the measurement of the nEDM can shed light on unanswered questions of fundamental physics such as baryon asymmetry, the strong CP problem, and extensions of the Standard Model such as supersymmetry.
The first part of this dissertation relates to the development of a new source of ultracold neutrons (UCNs) based on the conversion of cold neutrons, produced by a dedicated spallation source, to UCNs by downscattering in superfluid 4He. This new source will enable the desired statistical reach of the experiment. Prior to the construction of the new source, a prototype source was operated at TRIUMF from 2017 to 2019, and was used to perform experiments on UCN production, storage, and transport to assist in the design of the new source. This dissertation describes the results of a subset of those experiments, relating to the production and lifetime of UCNs in superfluid 4He.
The second part relates to the design of the TUCAN EDM spectrometer, which implements Ramsey's method of separated oscillating magnetic fields to search for a shift in precession frequency associated with the presence of a non-zero nEDM in a large electric field. To achieve the desired sensitivity, the spectrometer must be designed to minimize systematic uncertainty. The calculations and simulations described here demonstrate the requirements to achieve this goal. This work is largely focused on the design of the central region of the spectrometer, which contains the UCNs and applies the electric field. This includes the development of a prototype cell and characterization of its storage properties, simulation studies of the electric fields and impact of magnetic properties, and measurements of ferromagnetic contamination in components of the central region.
Event Location:
HENN 309
Event Time:
Monday, January 13, 2025 | 4:00 pm - 5:00 pm
Event Location:
HEBB 116
Add to Calendar
2025-01-13T16:00:00
2025-01-13T17:00:00
Building Rocky Planets
Event Information:
Abstract:
Early in our solar system’s evolution, thousands of rocky planetesimals, little planets the size of cities or continents, formed in just a few million years. Heat from the decay of a short-lived radioactive element caused melting in many planetesimals. Dense iron-nickel metal sank and formed cores in the planetesimals, surrounded by less-dense silicate mantles, the same structure that Earth and the other rocky planets have. Over the next few tens of millions of years many planetesimals crossed paths catastrophically. Colliding worlds merged and eventually formed complete rocky planets. Rocky planets are expected to have melted significantly or perhaps completely, and likely more than once each, because of the heat of these impacts. The resulting magma oceans are a clean starting point for forward modeling of planetary evolution, using the decades of lab- and field-based information on how silicate magmas solidify. How much, then, are variations in the evolution of planets due to differences in their planetesimal building blocks prior to magma ocean formation? What makes, in the end, a habitable planet? The spectrum of possible planetesimal structures and compositions motivated our successful proposal for the NASA Psyche mission, to visit the metallic asteroid (16) Psyche. I’ll present what is known and hypothesized about building rocky planets, and also about how space missions are helping to answer questions.
Bio:
Lindy Elkins-Tanton is a Foundation and Regents Professor in the School of Earth and Space Exploration. She is also the vice president of the ASU Interplanetary Initiative, and the Principal Investigator (PI) of the Psyche mission, selected in 2017 as the 14th in NASA’s Discovery program.
Her research includes theory, observation, and experiments concerning terrestrial planetary formation, magma oceans, and subsequent planetary evolution including magmatism and interactions between rocky planets and their atmospheres. She also promotes and participates in education initiatives, in particular, inquiry and exploration teaching methodologies, and leadership and team-building for scientists and engineers.
She has led four field expeditions in Siberia, as well as participated in fieldwork in the Sierra Nevada, the Cascades, Iceland, and the Faroe Islands.
Professor Elkins-Tanton received her bachelor's and master's degrees from MIT in 1987, and then spent eight years working in business, with five years spent writing business plans for young high-tech ventures. She then returned to MIT for a doctorate. She spent five years as a researcher at Brown University, followed by five years on MIT faculty, before accepting the directorship of the Department of Terrestrial Magnetism at the Carnegie Institution for Science. In 2014, she moved to the directorship at Arizona State University.
She serves on the Standing Review Board for the Europa mission, and served on the Mars panel of the Planetary Decadal Survey and on the Mars 2020 Rover Science Definition Team.
Professor Elkins-Tanton is a two-time National Academy of Sciences Kavli Frontiers of Science Fellow and served on the National Academy of Sciences Decadal Survey Mars panel. In 2008 she was awarded a five-year National Science Foundation CAREER award, and in 2009 was named Outstanding MIT Faculty Undergraduate Research Mentor. In 2010 she was awarded the Explorers Club Lowell Thomas prize. The second edition of her six-book series "The Solar System," a reference series for libraries, was published in 2010; the book "Earth," co-authored with Jeffrey Cohen, was published in 2017; and Harper Collins published her memoir, "A Portrait of the Scientist as a Young Woman" in 2022. Asteroid (8252) Elkins-Tanton and the mineral elkinstantonite were named for her.
In 2013 she was named the Astor Fellow at Oxford University, in 2016 she was named a fellow of the American Geophysical Union, and in 2018 a member of the American Academy of Arts and Sciences. In 2020 the National Academy of Sciences awarded her the Arthur L. Day Prize and Lectureship, and in 2021 she was elected to the National Academy of Sciences.
Learn more:
View her profile: https://search.asu.edu/profile/2437950
Check out her book! https://www.amazon.com/Asteroids-Meteorites-Comets-Solar-System/dp/081605195X
Watch her video: "Building a positive human space future" - Linda Elkins-Tanton interviewed by IAC TV: https://www.youtube.com/watch?v=rQdMbWbO_oA
Event Location:
HEBB 116
Event Time:
Thursday, January 9, 2025 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar
2025-01-09T10:00:00
2025-01-09T11:00:00
How nonlinearity distorts the evidence for photoinduced superconductivity
Event Information:
Over a decade of research has suggested that some metallic compounds can be transformed into superconductors by illuminating them with intense beams of laser light. Recently, we have shown that the experimental evidence for this effect could literally be an optical illusion produced by the high-intensity laser illumination. By examining several influential results on photoinduced superconductivity in K3C60, we have identified a fundamental flaw in their analysis that exaggerates the apparent photoinduced changes to the conductivity. When we account for this error, we find evidence that photoexcitation produces a moderate enhancement of the conductivity, but that there is no need to appeal to a photoinduced phase transition to a superconducting state. Subsequent work on K3C60 has provided quantitative support for our analysis. After discussing our reanalysis of experiments on K3C60, I will describe how this error also distorts the evidence for photoinduced superconductivity in the normal state of cuprate superconductors and in the charge-transfer salt BEDT-TTF. Finally, I will discuss how our reinterpretation raises new and interesting questions about the interaction of light with matter.
Event Location:
BRIM 311
Event Time:
Monday, January 6, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar
2025-01-06T16:00:00
2025-01-06T17:00:00
Finding Relativistic Stellar Explosions as Fast Optical Transients
Event Information:
Abstract:
For the last half-century, relativistic outflows accompanying the final collapse of massive stars have predominantly been detected via high-energy emission, as long-duration gamma-ray bursts (GRBs). Yet, it has long been hypothesized that GRBs are the tip of the iceberg of relativistic stellar explosions, because the conditions required to produce and detect a GRB are contrived. I will present results from a search for relativistic stellar explosions using optical time-domain surveys. The emerging zoo includes afterglows at cosmological distances with no detected GRB, supernovae with luminous X-ray and radio emission, and a mysterious class of "fast blue optical transients" with minute-timescale optical flares at supernova-like luminosities. An understanding of the origin of these events and their relation to GRBs will be enabled by upcoming time-domain surveys in other bands, including X-ray, UV, and submillimeter.
Bio:
Anna Ho's research uses telescopes located all over the world and in space to study the lives and deaths of stars and the physics of those phenomena and other energetic cosmic events. She uses wide-field surveys along with targeted observations from gamma-ray to radio wavelengths, and works to understand the physical processes governing the observed emission. She is an active member of several international collaborations, and serves as co-chair of the gamma-ray bursts working group for the ULTRASAT mission.
Learn More:
See Anna's faculty webpage from Cornell University, here: https://astro.cornell.edu/anna-yq-ho
Find her personal website here: https://annayqho.github.io/
What are long-duration gamma-ray bursts (GRBs): Imagine the Universe!
What are fast blue optical transients: Dying stars’ cocoons might explain fast blue optical transients - Northwestern Now
What is the ULTRASAT mission: Ultraviolet Transient Astronomy Satellite (ULTRASAT)
Event Location:
HENN 318
Event Time:
Thursday, December 19, 2024 | 10:00 am - 11:00 am
Event Location:
Via Zoom
Add to Calendar
2024-12-19T10:00:00
2024-12-19T11:00:00
Ultrafast photoemission studies of bulk and exfoliated Ta2NiSe5
Event Information:
Abstract:
This thesis details the development of a 6.2 eV laser-based time- and angle-resolved photoemission spectroscopy (TR-ARPES) apparatus with micro-scale spatial resolution for the study of equilibrium and non-equilibrium properties of inhomogeneous and exfoliated samples. To demonstrate the performance of this apparatus, we spatially resolve the sample inhomogeneities giving rise to spectral broadening of the surface state of the topological insulator Bi2Se3 observed when increasing the spot-size of the 6.2 eV source incident on the sample surface.
We then explore the dynamic properties of the correlation-driven ground state of candidate excitonic insulator Ta2NiSe5. Ta2NiSe5 undergoes a semimetal-to-insulator phase transition below 328 K, accompanied by a lattice distortion from an orthorhombic-to-monoclinic structure. Because both electron-phonon and excitonic interactions can give rise to the bandgap-opening, distinguishing between the contributions of both degrees-of-freedom is theoretically and experimentally challenging. The approach presented in this thesis is to examine the change in spectral lineshape width, related to quasiparticle lifetimes, upon photodoping with a 1.55 eV pump-pulse. The experimental results are directly compared to theoretical many-body simulations, revealing that the bandgap of Ta2NiSe5 originates from predominantly electronic contributions with a much smaller, but necessary, contribution from electron-phonon coupling.
In an effort to further elucidate the electronic and lattice contribution, we exfoliate Ta2NiSe5 on Au(111) using an in-situ exfoliation method and probe the sample with our micro-ARPES apparatus. Low-dimensional studies have been shown to induce electronic states that differ from their bulk counterparts due to the confinement, and may enhance exciton binding energies due to reduced screening of the electron-hole Coulomb interaction. In this study, we explore the emergence of an in-gap state, indicating a phase transition of ultrathin Ta2NiSe5 on Au(111) to a metallic state. The study is extended to the time-domain, where we observe the metallic-like response of ultrathin Ta2NiSe5 to a high-fluence 1.55 eV pump-pulse, and directly compare to the more familiar insulating-like region of the sample where we photo-induce a semimetallic phase. Overall, this thesis work explores the tunability of the bandgap of Ta2NiSe5 through photoexcitation, dimensionality, and carrier doping, demonstrating how we can manipulate the electronic properties, and even induce phase transitions, through manipulation of the physical and electrostatic environment of the material.
Event Location:
Via Zoom
Event Time:
Thursday, December 12, 2024 | 1:00 pm - 2:00 pm
Event Location:
AMPEL building, Room 311
Add to Calendar
2024-12-12T13:00:00
2024-12-12T14:00:00
Layer-Dependent Electronic Structure and Magnetic Transition Evolution in Two-Dimensional Ferromagnetic van der Waals Films
Event Information:
Abstract:In this work, we explore what happens to a magnet when it is to only a few layers of atoms thick. To do this we grow crystals of Fe$_3$GeTe$_2$ with a technique akin to atomic spray paint, which allows for the precise control of atomic ratios to approach a nearly perfect stoichiometry.
We first demonstrate the wafer-scale synthesis of high-quality, single-crystalline FGT films with precise control over layer thickness from 1 to 10 quintuple layers (QLs). With this layer control, we are able to perform transport measurements that reveal robust ferromagnetism across all layer numbers, with drastic thickness-dependent Curie temperatures evolution from 1-4 layers.
We then employ angle-resolved photoemission (ARPES) spectroscopy and density functional theory calculations, to map the evolution of the electronic band structure with increasing layer number, identifying emergent bands and quantifying the effects of interlayer coupling.
Carrier Density measurements are then performed for all thicknesses as a function of temperature and compared to the density of states near the Fermi energy observed in ARPES. Surprisingly we observe a constant normalized carrier density per QL at the Curie temperature across different thicknesses, suggesting a universal mechanism underlying the ferromagnetic transition. We then discuss the applicability of itinerant electron-dominated or mediated mechanisms for magnetism and the unique Fe site contributions.:In this work, we explore what happens to a magnet when it is to only a few layers of atoms thick. To do this we grow crystals of Fe$_3$GeTe$_2$ with a technique akin to atomic spray paint, which allows for the precise control of atomic ratios to approach a nearly perfect stoichiometry.
We first demonstrate the wafer-scale synthesis of high-quality, single-crystalline FGT films with precise control over layer thickness from 1 to 10 quintuple layers (QLs). With this layer control, we are able to perform transport measurements that reveal robust ferromagnetism across all layer numbers, with drastic thickness-dependent Curie temperatures evolution from 1-4 layers.
We then employ angle-resolved photoemission (ARPES) spectroscopy and density functional theory calculations, to map the evolution of the electronic band structure with increasing layer number, identifying emergent bands and quantifying the effects of interlayer coupling.
Carrier Density measurements are then performed for all thicknesses as a function of temperature and compared to the density of states near the Fermi energy observed in ARPES. Surprisingly we observe a constant normalized carrier density per QL at the Curie temperature across different thicknesses, suggesting a universal mechanism underlying the ferromagnetic transition. We then discuss the applicability of itinerant electron-dominated or mediated mechanisms for magnetism and the unique Fe site contributions.
Event Location:
AMPEL building, Room 311