Events List for the Academic Year
Event Time:
Thursday, January 23, 2025 | 3:00 pm - 4:00 pm
Event Location:
Outside of HENN 200 (atrium)
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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
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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)
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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
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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)
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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
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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
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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
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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
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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
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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
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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
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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
Event Time:
Thursday, December 12, 2024 | 10:00 am - 11:00 am
Event Location:
BRIM 311
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2024-12-12T10:00:00
2024-12-12T11:00:00
Majorana bound states in artificial Kitaev chains
Event Information:
The Kitaev chain model predicts the ability to engineer localized Majorana bound states: non-Abelian zero-energy excitations that are protected from local perturbations, which can be utilized for realizing robust quantum computation schemes. Recent work on InSb nanowires demonstrated that the ingredients for a minimal Kitaev chain, consisting of two sites, can be engineered by coupling quantum dots (QDs) via two second-order processes: crossed Andreev reflection and elastic co-tunnelling. To open up the path to more complex experiments, we implemented this system in a two-dimensional electron gas (2DEG). In this talk, I will detail the theoretical background and our experimental implementation of the Kitaev chain in the InSbAs 2DEG platform. I will highlight recent results obtained on a chain consisting of three quantum dots, where we find that the presence of zero energy modes on the outer QDs is correlated with a bulk excitation gap in the middle QD, demonstrating key properties of the Kitaev chain.
Event Location:
BRIM 311
Event Time:
Tuesday, December 10, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2024-12-10T16:00:00
2024-12-10T17:00:00
Special Colloquium: The NANOGrav Experiment: Current Results and Future Directions
Event Information:
Abstract:
Galaxy mergers are a standard aspect of galaxy formation and evolution, and most large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz to microhertz regime. An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in the nanohertz band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent evidence for a gravitational wave background, and efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers.
Bio:
Dr. Chiara Mingarelli is an Assistant Professor of Physics at Yale University and a prominent researcher in the field of gravitational wave astrophysics. Her work focuses on using pulsar timing arrays to detect nanohertz-frequency gravitational waves, particularly those generated by supermassive black hole binaries. She has held key leadership roles, including serving on NASA's Physics of the Cosmos Executive Committee and co-chairing the Gravitational Wave Science Interest Group. Dr. Mingarelli is also a Full Member of the NANOGrav collaboration, contributing to the discovery of the gravitational wave background. An advocate for diversity in science, she previously served as the Ada Lovelace Director of Diversity at the Flatiron Institute. Dr. Mingarelli has been widely recognized for her contributions, with over 100 refereed papers with 16,000 citations, and numerous grants from NASA and the National Science Foundation.
Learn More:
See Chiara's personal website here: https://www.chiaramingarelli.com/
Read her guest blog for Scientific American: https://www.scientificamerican.com/blog/guest-blog/searching-for-the-gravitational-waves-ligo-can-t-hear/
View her Yale faculty page: https://astronomy.yale.edu/people/chiara-mingarelli
Watch her videos:
Frontiers of pulsar timing array experiments: https://www.youtube.com/watch?v=uDdxcS0HeeU
Unlocking the Universe: Chiara Mingarelli on Pulsar Timing Arrays & Gravitational Waves: https://www.youtube.com/watch?v=tn--gIGKmJw
79 - NanoGRAV's Big Gravitational Wave Discovery (Ft. Chiara Mingarelli) | Why This Universe Podcast: https://www.youtube.com/watch?v=__otsacCqhY
Links:
NANOGrav Collaboration: https://nanograv.org/collaboration/overview
Pulsar Timing Array Group: https://perimeterinstitute.ca/news/international-group-pulsar-timing-arrays-announce-gravitational-wave-detection
What are gravitational waves? https://www.ligo.caltech.edu/page/what-are-gw
Flatiron Institute: https://flatironschool.com/blog/flatiron-school-relaunches-lovelace-and-ford-fellowships/
NASA's Physics of the Cosmos group: https://pcos.gsfc.nasa.gov/
Event Location:
HENN 201
Event Time:
Monday, December 9, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
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2024-12-09T16:00:00
2024-12-09T17:00:00
Entering a new, data-driven era for precision cosmology: opportunities and challenges for machine learning
Event Information:
Abstract:
Despite the remarkable success of the standard model of cosmology, the inflationary lambda CDM model, at predicting the observed structure of the universe over many scales, very little is known about the fundamental nature of its principal constituents: the inflationary field(s), dark matter, and dark energy. In this talk, I will give a brief overview of the successes of the inflationary lambda CDM model and discuss how, in the coming years, new surveys and telescopes will provide an opportunity to probe these unknown components. These surveys will produce unprecedented volumes of data, the analysis of which can shed light on the equation of state of dark energy, the particle nature of dark matter, and the nature of the inflaton field. The analysis of this data using traditional methods, however, is entirely impractical. I will share my recent work focused on developing machine learning tools for cosmological data analysis and discuss how these tools can help us overcome some of the most important computational challenges of analyzing data from the next generation of sky surveys.
Bio:
Laurence Perreault-Levasseur is the Canada Research Chair in Computational Cosmology and Artificial Intelligence. She is an assistant professor at Université de Montréal and an associate academic member of Mila – Quebec Artificial Intelligence Institute. Perreault-Levasseur’s research focuses on the development and application of machine learning methods to cosmology.
She is also a Visiting Scholar at the Flatiron Institute in New York City. Prior to that, she was a research fellow at their Center for Computational Astrophysics, and a KIPAC postdoctoral fellow at Stanford University.
For her PhD degree at the University of Cambridge, she worked on applications of open effective field theory methods to the formalism of inflation. She completed her BSc and MSc degrees at McGill University.
Learn More:
See her faculty webpage here: Laurence PERREAULT-LEVASSEUR - Département de physique - Université de Montréal
Read more about her research here: Laurence Perreault Levasseur – Interaction
Event Location:
HENN 318
Event Time:
Monday, December 9, 2024 | 2:30 pm - 3:30 pm
Event Location:
HENN 318
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2024-12-09T14:30:00
2024-12-09T15:30:00
PHAS Monday Tea!
Event Information:
Event Information:
Welcome everyone to Monday Tea!
This is our last Monday Tea event for 2024! Stay tuned for our 2025 schedule, which will be posted in our events calendar.
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 in the EDI Community Building Working Group:
Jess McIver
Adele Ruosi
Megan Bingham
Evan Goetz
Mona Berciu
Howard Li
Mandana Amiri
See you there!
Event Location:
HENN 318
Event Time:
Monday, December 9, 2024 | 12:30 pm - 2:03 pm
Event Location:
Graduate Student Centre (6371 Crescent Road), Room 203
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2024-12-09T12:30:00
2024-12-09T14:03:00
Anomalies in the cosmic microwave background
Event Information:
Abstract:
Over the past century, our understanding of the Universe has grown dramatically. Today, scientists use a model that requires just six key numbers to describe how the Universe evolved. Yet, some big mysteries remain unsolved. In my thesis, I explore two of these mysteries.
The first involves a signal that might be hidden by our movement through the Universe. Since Earth -- and our entire Galaxy -- is moving, the signals we observe are altered, via the Doppler effect. This makes it hard to separate universe-spanning signals from those caused by our motion. I investigate ways to tell them apart.
The second mystery, cosmic birefringence, rotates the light as it moves through the Universe, like light through a crystal. This could only be caused by a new type of field, like gravity or electromagnetism, and is potentially an observable caused by dark matter or dark energy.
Event Location:
Graduate Student Centre (6371 Crescent Road), Room 203
Event Time:
Sunday, December 8, 2024 | 1:15 pm - 3:00 pm
Event Location:
HEBB 100
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2024-12-08T13:15:00
2024-12-08T15:00:00
2024 Faraday Show
Event Information:
We are thrilled to announce that our annual Faraday Show will be held on Sunday December 8th, in-person, on the UBC-Vancouver campus in HEBB 100.
The Faraday Show is UBC’s annual science lecture, designed for children and all those who are ‘young at heart’. It is presented by UBC Physics & Astronomy students, faculty and staff.
This year’s theme is: "Physics in your House!". We will answer questions such as, How does the best fire alarm work? Where does static electricity come from? Why do your windows mist up in the winter? All these and more will be answered through fun demonstrations and hands-on activities!
Show schedule:
Pre-Show (table top demonstrations): 1:15PM – 1:55PM
Stage Show (stage presentations): 2:00PM – 3:00PM
This show is FREE! We ask that you please bring non-perishable food items to support Greater Vancouver Food Bank member, The Kettle Society. No RSVP required, although we recommend arriving 15-20 minutes earlier for good seats.
*Planning Tip:
Plan a day on campus! Mention “Faraday Show” and get 50% off admission at the Beaty Biodiversity Museum on Sunday December 8th, between 10am-5pm!
Event Location:
HEBB 100