Events List for the Academic Year
Event Time:
Thursday, March 24, 2022 | 4:00 pm - 5:00 pm
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2022-03-24T16:00:00
2022-03-24T17:00:00
More Than Pretty Pictures
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Abstract
Images and figures — visual representations of scientific data and concepts — are critical components of science and engineering research. They communicate in ways that words cannot. They can clarify or strengthen an argument and spur interest into the research process.
But it is important to remember that a visual representation of a scientific concept or data is a re-presentation and not the thing itself –– some interpretation or translation is always involved. Just as writing a journal article, one must carefully plan what to "say," and in what order to "say it." The process of making a visual representation requires you to clarify your thinking and improve your ability to communicate with others.
In this talk, I will show my own approach to creating depictions in science and engineering—the successes and failures. Included will be a discussion about how far can we go when "enhancing" science images.
Bio
Science photographer Felice Frankel is a research scientist at the Massachusetts Institute of Technology in the department of Chemical Engineering with additional support from Mechanical Engineering. She joined MIT in 1994. Frankel is a Fellow of the American Association for the Advancement of Science, and was awarded a Guggenheim Fellowship among others.
Working in collaboration with scientists and engineers, Felice Frankel's images have appeared in outlets such as National Geographic, Nature, Science, Angewandte Chemie, Advanced Materials, Materials Today, PNAS, Newsweek, Scientific American, Discover, Popular Science and New Scientist, among others. She is working on her 8th book, a series of handbooks: "THE VISUAL ELEMENTS, communicating science and engineering."
Website: www.felicefrankel.com
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Thursday, March 24, 2022 | 10:00 am - 11:00 am
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2022-03-24T10:00:00
2022-03-24T11:00:00
Marlou Slot: Atom by atom and layer by layer: Designing and realizing electronic quantum matter
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https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Speaker: Marlou Slot; National Institute of Standards and Technology (NIST) - Gaithersburg, Maryland, United States
Title: Atom by Atom and Layer by Layer: Designing and Realizing Electronic Quantum Matter
Abstract: Quantum simulators are a versatile tool to study the behavior of quantum matter in a controlled way. Elusive or complex quantum systems are simulated using accessible quantum systems that can be manipulated at will. While platforms based on, among others, ultracold atoms and photons are well-established, electronic platforms are currently being developed.
The scanning tunneling microscope (STM) is uniquely suited to create and manipulate electronic 2D potential landscapes at will in-situ. By atomic-scale patterning of the 2D electron gas at specific metal surfaces, the electrons can be molded into electronic lattices with nearly any geometry. In this talk, I will present CO molecules adsorbed on a Cu(111) surface as a highly-tunable electronic quantum simulator, in which the lattice geometry, the orbital degree of freedom, the dimension and the topology can be tailored [1-4]. Moving beyond the in-situ approach, ex-situ nanofabricated twisted van der Waals devices pave the way to study electron-electron interactions in tailor-made 2D potential landscapes [5]. I will demonstrate high-resolution gate-tunable Landau level spectroscopy and signatures of correlated states in twisted double bilayer graphene, expanding the quantum simulation toolkit from atom by atom to layer by layer.
[1] M. R. Slot et al., Nat. Phys. 13, 672 (2017)
[2] S. N. Kempkes and M. R. Slot et al., Design and characterization of electrons in a fractal geometry, Nat. Phys. 15, 127 (2019)
[3] M. R. Slot and S. N. Kempkes et al., p-Band Engineering in Artificial Electronic Lattices, PRX 9, 011009 (2019)
[4] S. N. Kempkes and M. R. Slot et al., Robust zero-energy modes in an electronic higher-order topological insulator, Nat. Mater. 18, 1292 (2019)
[5] D.M. Kennes et al., Moiré heterostructures as a condensed-matter quantum simulator, Nat. Phys. 17, 155 (2021)
Bio: Marlou Slot is a Rubicon Postdoctoral Fellow and NIST-Georgetown PREP Fellow working with Dr. Joseph Stroscio at the National Institute of Standards and Technology. She obtained her PhD from Utrecht University working with Prof. Daniel Vanmaekelbergh and Prof. Ingmar Swart. Prior to that, she obtained her undergraduate degree from RWTH Aachen University and EPFL Lausanne and she was a research assistant at Forschungszentrum Jülich. Her research interests focus on designer quantum matter realized and/or measured using scanning probe microscopy, including van der Waals heterostructures and in-situ patterned surfaces.
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Monday, March 21, 2022 | 3:00 pm - 4:00 pm
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2022-03-21T15:00:00
2022-03-21T16:00:00
White dwarf crystallization as revealed by Gaia
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White dwarfs are stellar embers that simply cool down for the rest of time, eventually freezing into a solid state. This predictable evolution makes them precise cosmic clocks; they have been used for decades to measure the ages of stellar populations. But data from the Gaia space observatory is now challenging our understanding of white dwarf evolution and calling into question the accuracy of this age dating technique. The cooling process appears to be much more delayed by the onset of crystallization than predicted by current models. In this talk, I will present my recent theoretical work aimed at improving the constitutive physics of white dwarf cooling models (in particular the physics of core crystallization) and discuss outstanding uncertainties that should be addressed before white dwarf cosmochronology can reach its full potential.
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Thursday, March 17, 2022 | 4:00 pm - 5:00 pm
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2022-03-17T16:00:00
2022-03-17T17:00:00
Why I Count Calories for a Living
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Calorimetry measures heat effects, so why should one care? Enthalpies of formation and phase transformation sing about making and breaking chemical bonds. Heat capacities and entropies dance about how atoms and electrons jostle each other, move, and disorder. Combining thermodynamic and structural studies provides illuminates what materials form in nature, in the lab, and in technology. I illustrate the insights gained from calorimetry by three examples from our work. (1) Zinc sulfide (ZnS) is important as a semiconductor and an ore mineral. It occurs in two polymorphs, sphalerite and wurtzite. Our recent calorimetric studies have highlighted the importance of surface energy in changing the thermodynamic stability of these polymorphs, especially at the nanoscale, explaining their otherwise puzzling occurrences. (2) Pyrochlore is an ordered derivative of the simple fluorite structure and it has been proposed as a nuclear waste form. However, it is subject to radiation damage, leading to disorder and loss of crystallinity. A combination of neutron diffraction and calorimetry has shown that the nominally disordered or amorphized products of heavy ion irradiation contain persistent nanodomains of ordered weberite structure which strongly affect stability and physical properties, complicating simple pictures of radiation tolerance. (3) Zeolites and metal organic frameworks contain immense structural porosity, increasing their volume many times over that of a dense phase. Calorimetry has shown that the energetic penalty of porosity is amazingly small, enabling the synthesis, stability, and persistence of many new and useful materials. In all these cases, the microscopic structural and macroscopic thermochemical insights work together to understand and predict the existence and behavior of materials.
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Thursday, March 17, 2022 | 10:00 am - 11:00 am
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2022-03-17T10:00:00
2022-03-17T11:00:00
Alexandra Navrotsky: Recent Developments in High Temperature Calorimetry
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https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Speaker: Alexandra Navrotsky - Center for Materials of the Universe (MotU) , Arizona State University
Title: Recent developments in high temperature calorimetry
Abstract: A variety of high temperature calorimetric techniques have recently advanced for application to refractory oxides and related materials. These include improvements in oxide melt solution calorimetry at temperatures up to 1500 ⁰C, differential thermal analysis to 2500 ⁰C, and “drop-n-catch” calorimetry to 3000 ⁰C. Used together, these methods enable one to draw a more complete picture of phase stability, order-disorder, melting and crystallization, and dissolution of solids in silicate melts. These methods will be illustrated using examples from rare earth materials chemistry. New developments in the calorimetry of chalcogenides and mixed anion materials will also be presented. The synergy among calorimetry, first principles calculations and computations of phase diagrams will be emphasized.
Bio: Alexandra Navrotsky - Professor, School of Molecular Sciences and School for Engineering of Matter, Transport and Energy
Affiliated Faculty Member, School of Earth and Space Exploration
Director, Center for Materials of the Universe
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Event Time:
Monday, March 14, 2022 | 3:00 pm - 4:00 pm
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2022-03-14T15:00:00
2022-03-14T16:00:00
Galaxy Evolution in Dense Environments
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As the universe evolves star-forming galaxies transform into
passively-evolving red galaxies. These transformations are due to a
combination of internal processes, like feedback from an active
galactic nucleus, as well as environmental processes. I will review
the ways in which host environment can affect the properties of
galaxies and then present some of our recent work on group and cluster
galaxies in the local universe. Previous work has found that the star
formation rates of satellite galaxies depend on the mass of their host
halo. We explore how galaxy quenching depends on the evolutionary
state of their host environment as traced by both member dynamics and
X-ray properties. I will discuss how these trends can be used to
constrain the mechanisms at play in environmentally-driven galaxy
evolution and end with some recent work on ram pressure stripped
galaxies in low-redshift clusters.
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Thursday, March 10, 2022 | 4:00 pm - 5:00 pm
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2022-03-10T16:00:00
2022-03-10T17:00:00
Robophysics: robotics meets physics
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Abstract: Robots will soon move from the factory floor and into our lives (e.g. autonomous cars, package delivery drones, and search-and-rescue devices). However, compared to living systems, robot capabilities in complex environments are limited. I believe the mindset and tools of physics can help facilitate the creation of robust self-propelled autonomous systems. This “robophysics” approach – the systematic search for novel dynamics and principles in robotic systems – can aid the computer science and engineering approaches which have proven successful in less complex environments. The rapidly decreasing cost of constructing sophisticated robot models with easy access to significant computational power bodes well for such interactions. Drawing from examples in the work of my group and our collaborators, I will discuss how robophysical studies have inspired new physics questions in low dimensional dynamical systems (e.g. creation of analog quantum mechanics and gravity systems) and soft matter physics (e.g. emergent capabilities in ensembles of active “particles”), have been useful to develop insight for biological locomotion in complex terrain (e.g. control targets via optimizing geometric phase), and have begun to aid engineers in the creation of devices that begin to achieve life-like locomotor abilities on and within complex environments (e.g. semi-soft myriapod robots).
Bio: Dr. Daniel I. Goldman is a Dunn Family Professor in the School of Physics at the Georgia Institute of Technology and a Georgia Power Professor of Excellence. Prof. Goldman became a faculty member at Georgia Tech in January 2007. He is an adjunct member of the School of Biology and is a member of the Interdisciplinary Bioengineering Graduate Program. Prof. Goldman's research program broadly investigates the interaction of biological and physical systems with complex materials like granular media. In particular, he integrates laboratory experiment, computer simulation, and physical and mathematical models to discover principles of movement of a diversity of animals and robots in controlled laboratory substrates. He received his S.B. in physics at the Massachusetts Institute of Technology in 1994. He received his PhD in Physics in 2002 from the University of Texas at Austin, studying nonlinear dynamics and granular media. From 2003-2007 he did postdoctoral work in the Department of Integrative Biology at UC Berkeley studying locomotion biomechanics. Prof. Goldman is a Fellow of the American Physical Society (2014), and has received an NSF CAREER/PECASE award, a DARPA Young Faculty Award, a Burroughs Wellcome Fund Career Award at the Scientific Interface, and the UT Austin Outstanding Dissertation in Physics (2002-2003).
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Thursday, March 10, 2022 | 10:00 am - 11:00 am
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2022-03-10T10:00:00
2022-03-10T11:00:00
Inna Vishik: Electronic Correlations and Topology across Tc in a Magnetic Weyl Semimetal
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https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Speaker: Inna Vishik - Associate Professor in Physics and Astronomy at UC Davis
Abstract: Co3Sn2S2 is a magnetic Weyl semimetal below its Curie temperature (Tc) of 177K. I will discuss our recent spatial and temperature-dependent angle-resolved photoemission spectroscopy (ARPES) studies in this system. Across Tc, we observe signatures of a topological phase transition, but also observe changes in bulk bands which are inconsistent with a simple lifting of exchange interactions, suggesting enhanced electronic correlations in the regime without long-range magnetic order. I will also discuss spatial-dependent microARPES data which quantify the characteristic differences between Sn- and S- terminated surfaces.
Ref: Rossi, Ivanov, et al, PRB 104, 155115 (2021)
Bio: Inna Vishik is an Associate Professor in Physics and Astronomy at UC Davis. Since 2016, her lab has been performing ARPES and ultrafast optics experiments to elucidate emergent phenomena in superconducting, correlated, and topological quantum materials. Prior to this, she received her PhD at Stanford and was subsequently a Pappalardo Postdoctoral fellow at MIT.
Event Location:
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Event Time:
Monday, March 7, 2022 | 3:00 pm - 4:00 pm
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2022-03-07T15:00:00
2022-03-07T16:00:00
Alignment of Galaxies with Large Scale Structure
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The internal structure of galaxies is strongly affected by the gravitational influence of surrounding matter, on scales up to several megaparsecs. For example, galaxies are tidally torqued by surrounding galaxies and clusters. Conversely, a single massive elliptical galaxy can have a significant gravitational influence on surrounding satellite galaxies. To quantify the interplay between galaxies and surrounding structure on larger scales, we have done a study of the alignment of galaxy images with the surrounding large scale structure, using data from the Sloan Digital Sky Survey (SDSS) Legacy Survey. We find that galaxies have a statistically significant tendency ( > 5 sigma ) to align parallel to the larger scale structure surrounding them, on scales up to 7.5 Mpc. This signal is driven primarily by red galaxies that are more luminous than the sample mean ( M_r < -21 ). Blue galaxies do not have a statistically significant tendency to align with the larger scale structure. Both the lack of alignment for blue disk galaxies and the alignment for red elliptical galaxies provide clues to help us decipher the influence of large scale structure on individual galaxies, and vice versa.
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Event Time:
Thursday, March 3, 2022 | 4:00 pm - 5:15 pm
Event Location:
Henn 201
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2022-03-03T16:00:00
2022-03-03T17:15:00
3 Minute Thesis - Physics & Astronomy Heat
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3 Minute Thesis Competition, Physics and Astronomy Heat
Thursday March 3, 2022 4-5:15pm in Colloquium, live in HENN 201
The Three Minute Thesis (3MT) is an academic competition that assists current graduate students with fostering effective presentation and communication skills. Participants have just three minutes to explain the breadth and significance of their research project to a non-specialist audience. Over 200 universities participate in this fun, highly informative and very entertaining event. UBC was one of the first Universities in North America to host a 3MT competition.
Our PHAS department has been participating since 2014,and almost every year we've had PHAS grad students advance to the UBC Semi-finals, and almost every year, through to the UBC 3MT FINALs.
Register for the 2022 UBC Physics and Astronomy Heat of 3MT
For full information, schedule, rules, eligibility, coaching sessions, judging criteria etc, see UBC 3 Minute Thesis
After the UBC PHAS 3MT heat, the top PHAS presentation(s) will advance to the UBC-wide Semifinals, and hopefully we'll have a PHAS grad make it through to the UBC Finals, and maybe even the Canadian nationals and the International 3MT competition again!
2022 UBC-wide 3MT Semi-Finals and Finals:
Semi-Final Date: Tuesday, March 8th, 12:00 - 2:00 pm + Wednesday, March 9th, 12:00 - 2:00 pm
Final Date: Wednesday, March 30th, 12:00 - 2:00 pm
Full details,
times for the UBC-wide Semi-Finals and Finals will be on the UBC 3MT schedule
The overall UBC 3MT winner will advance to the Western Canadian National 3MT Competition at U Winnipeg this year.
Check out some UBC finalists and watch their 3MTs from past years:
All UBC 3MT finalists from 2011-2021, including PHAS student Sarah Morris, who won the 2021 UBC People's Choice Award last year
In 2018, PHAS student Andrew Robertson placed first in the UBC-wide semi-finals, first in the UBC 3MT FINAL, and he proceeded to the Western Canadian Finals in Regina, and earned a place in the 3MT International competition! Check out: Andrew Robertson's 3 Minute Thesis
Preparing for the 3MT
UBC Graduate Studies offers Resources to help you prepare for 3MT
Questions? Janis McKenna (janis@physics.ubc.ca)
Foster your comunications skills by presenting your research to a non-specialist audience in just 3 minutes. Network with other graduate students, gain exposure for your work, and win prizes! Physics & Astronomy
PHAS Graduate students - Register to be a participant at https://www.phas.ubc.ca/~janis/3MT
Event Location:
Henn 201
Event Time:
Thursday, March 3, 2022 | 10:00 am - 11:00 am
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2022-03-03T10:00:00
2022-03-03T11:00:00
Ke Zou: Recent progress on understanding the superconductivity of bulk and monolayer FeSe
Event Information:
https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Speaker: Ke Zou
Abstract:
The physics of high-temperature superconductors is usually governed by the interplay of the spin and charge degrees of freedom. FeSe has the simplest chemical composition among Fe-based superconductors, yet monolayer FeSe on SrTiO3 substrate reports one of the highest superconducting transition temperatures. I will summarize the progress on understanding its superconductivity from my group and other groups in the recent couple of years. We will discuss the specific roles of charge transfer, spin magnetic moment, and phonon coupling in this system.
F. Li, I. Elfimov, and G.A. Sawatzky, “Modulation doping of the FeSe monolayer on SrTiO3”, submitted (2022).
C. Liu, H. Shin, A. Doll, H.H. Kung, R.P. Day, B.A. Davidson, J. Dreser, G. Levy, A. Damascelli, C. Piamonteze, and K. Zou, “High-temperature superconductivity and robustness against magnetic polarization in monolayer FeSe on EuTiO3”, npj Quantum Materials 6, 85 (2021).
C. Liu, R.P. Day, F. Li, R.L. Roemer, S. Zhdanovich, S. Gorovikov, T. Pedersen, J. Jiang, S. Lee, M. Schneider, D. Wong, P. Dosanjh, F.J. Walker, C.H. Ahn, G. Levy, A. Damascelli, G.A. Sawatzky, and K. Zou, “High-order replica bands in monolayer FeSe/SrTiO3 revealed by polarization-dependent photoemission spectroscopy”, Nature Communications 12, 4573 (2021).
Bio: Assistant Professor, Department of Physics and Astronomy - SBQMI
Research Focus: Our research interests are in the growth of complex oxide and chalcogenide films by molecular beam epitaxy and the studies of their properties and functions. We aim to achieve scientific and technological breakthroughs in new materials and new functional devices. We integrate molecular beam epitaxy synthesis with nanostructure fabrication and characterization techniques for physical and electronic structures, to explore and control the generated properties in new materials and in new forms of materials, such as in heterostructures and gated field-effect transistors.
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Event Time:
Wednesday, March 2, 2022 | 12:00 pm - 1:00 pm
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2022-03-02T12:00:00
2022-03-02T13:00:00
Seminar - Black Hole Collider Physics
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Hello, please join us over Zoom for a special seminar talk on Wed, March 2nd hosted by Assistant Professor candidate Julio Parra Martinez
Date & Time – Wednesday March 2 12:00-1:00pm
Seminar Topic: Black Hole Collider Physics
Abstract: From the flying cannonball of Newton to the free-falling elevator of Einstein, drawing connections between different dynamics has been essential in developing our understanding of gravitational physics. In this talk, I will describe how considering the scattering of black holes and gravitons can shed light on the dynamics of compact binary mergers observed at LIGO/VIRGO, and more generally on the two-body problem in General Relativity. I will explain how using modern ideas from collider and particle physics, such as quantum field theory, scattering amplitudes, and surprising relations between gluons and gravitons, we can calculate and constrain the outcome of such scattering experiments in classical gravity. From such calculations we can produce state-of-art results for current and future gravitational wave observatories, and open the door for further discovery as we enter a new era of precision gravitational physics.
https://ubc.zoom.us/j/67105140559?pwd=Ym1zakdmaWp6VW1XekRxY1g5UmlOZz09
Meeting ID: 671 0514 0559
Passcode: 563296
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Event Time:
Monday, February 28, 2022 | 3:00 pm - 4:00 pm
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2022-02-28T15:00:00
2022-02-28T16:00:00
Improved constraints on primordial gravitational waves using BICEP/Keck observations
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Cosmic inflation was postulated to solve the horizon, flatness and monopole problems that arise from the standard LCDM model. Inflation generically predicts the existence of primordial gravitational waves which would leave a unique degree-scale B-mode polarization pattern in the cosmic microwave background (CMB). If detected, this could serve as a probe to the early Universe and high energy physics inaccessible with existing particle accelerators. The BICEP/Keck experiments are a series of telescopes at the South Pole designed to search for this degree-scale B-mode signature in the CMB. Our latest release (BK18) includes new data collected through the 2018 season, and is the first to utilize observations from the 95GHz BICEP3 telescope. This result shows the tensor-to-scalar ratio r < 0.036 at 95% confidence with σ(r)=0.009, which is the tightest constraint to date on primordial gravitational waves.
In this talk, I will first present the instrument design of the BICEP telescopes, and describe the analysis and scientific findings of BK18.
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Wednesday, February 23, 2022 | 12:00 pm - 1:00 pm
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2022-02-23T12:00:00
2022-02-23T13:00:00
Hidden Sectors: From the Early Universe to Today
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Hidden Sectors: From the Early Universe to Today
In spite of the many successes of the Standard Model (SM) of particle physics, several important ingredients of our universe are still mysteries, including dark matter, the origin of the matter-antimatter asymmetry, and the physics underlying neutrino masses. These phenomena point to collections of as-yet unidentified new particles and forces called hidden sectors. Taking as a concrete example the recently proposed mechanism of freeze-in baryogenesis via dark matter oscillations, I will show how relatively simple extensions of the SM can give rise to rich dynamics in the early universe that resolve the open questions of the SM and point towards energy and length scales that are experimentally accessible today. I will then describe new efforts and proposals to discover cosmologically motivated hidden-sector particles using collider experiments, with complementarity between high- and low-energy colliders.
Join via Zoom
https://ubc.zoom.us/j/64832214108?pwd=VWR1TmoxNVo1ZHpaUHA0dU1xTkRqdz09
Meeting ID: 648 3221 4108
Passcode: 024707
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Event Time:
Thursday, February 17, 2022 | 4:00 pm - 5:00 pm
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2022-02-17T16:00:00
2022-02-17T17:00:00
Ars Scientia: An artist and a physicist walked into a glassblowing studio ...
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The UBC Ars Scientia collaboration brings together artists and scientists to identify fruitful areas for interdisciplinary work. I'll describe how it plunged this theoretical physicist into a messy (and fun!) glassblowing studio, why it saw me capturing explosions at 100,000 frames per second at the hospital, and how some serendipitous physics observations have taken me into the lab. Come learn a bit about the physics of glass and other avalanching systems, as well as how to make the most of an art and science collaboration!
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Event Time:
Thursday, February 17, 2022 | 10:00 am - 11:00 am
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2022-02-17T10:00:00
2022-02-17T11:00:00
Fazel Tafti: A New Paradigm for Colossal Magnetoresistance and Nonlinear Hall Effect
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https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Speaker: Fazel Tafti, Boston College
Abstract
Materials with strong magneto resistive responses are the backbone of spintronic technology, magnetic sensors, and hard drives. Among them, manganese oxides with a mixed valence and a cubic perovskite structure stand out due to their colossal magnetoresistance (CMR). A double exchange interaction underlies the CMR in manganates, whereby charge transport is enhanced when the spins on neighboring Mn3+ and Mn4+ ions are parallel. Prior efforts to find different materials or mechanisms for CMR resulted in a much smaller effect. In this talk, I present the observation of an enormous CMR at low temperatures in EuCd2P2 without manganese, oxygen, mixed valence, or cubic perovskite structure. EuCd2P2 has a layered trigonal lattice and exhibits antiferromagnetic ordering at 11 K. The magnitude of CMR (104%) in as-grown crystals of EuCd2P2 rivals the magnitude in optimized thin films of manganates. The magnetization, transport, and synchrotron X-ray data suggest that strong magnetic fluctuations are responsible for this phenomenon. The realization of CMR at low temperatures without heterovalency leads to a new regime for materials and technologies related to antiferromagnetic spintronics.
Biography:
Fazel Tafti completed his PhD at the University of Toronto with Prof. Steven Julian. His thesis was focused on developing transport experiments under ultrahigh pressures in diamond anvil cells. His first postdoc position at the University of Sherbrook with Prof. Louis Taillefer was focused on the thermal conductivity and thermoelectric measurements in iron-based superconductors under intense magnetic fields. He then changed fields from physics to chemistry and completed a second postdoc at Princeton University with Prof. Bob Cava. His research was focused on the chemical synthesis of topological and magnetic materials. He has been an assistant professor at Boston College (physics department) since 2016. His lab is interdisciplinary between physics, chemistry, and materials science.
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Event Time:
Monday, February 14, 2022 | 3:00 pm - 4:00 pm
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2022-02-14T15:00:00
2022-02-14T16:00:00
Probing relativistic gravity with radio astronomy
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We are experiencing a golden era in testing and exploring relativistic gravity.
Whether it is results from gravitational wave detectors, satellite or lab
experiments, radio astronomy plays an important complementary role.
Here one can mention the cosmic microwave background, black hole
imaging and, obviously, binary pulsars. This talk will provide an overview of
how these methods relate to each other, and will in particular focus on new
results from the study of binary pulsars, where we can test the behaviour
of strongly self-gravitating bodies with unrivalled precision.
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Event Time:
Monday, February 14, 2022 | 12:00 pm - 1:00 pm
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2022-02-14T12:00:00
2022-02-14T13:00:00
nEXO and the future of neutrinoless double beta decay
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The discovery that neutrinos have nonzero, but inexplicably small, masses hints that these particles may hold the key to unlocking physics beyond the Standard Model (BSM). In this talk, I will discuss the search for neutrinoless double beta decay (0νββ), a proposed form of radioactive decay that, if observed, would immediately demonstrate BSM physics. Specifically, discovery of 0νββ would establish a) violation of lepton number conservation, currently thought to be a fundamental symmetry of particle interactions, b) the generation of neutrino masses by a mechanism other than the Higgs, and c) possible connections between neutrino interactions and the dominance of matter over antimatter in the universe. These exciting possibilities have motivated a worldwide program to search for 0νββ using a wide variety of experimental techniques. I will describe the next generation of these efforts, focusing in particular on the nEXO experiment, which will be constructed over the next few years at the SNOLAB research facility in Sudbury, ON. nEXO is designed to reach a sensitivity two orders of magnitude beyond the reach of current experiments, pushing deep into unexplored parameter space. I will discuss nEXO’s design and some technical developments, other possible science that we can do with the nEXO detector, and will close with a discussion on scaling up the techniques used by nEXO to enable beyond-the-next-generation searches for new physics.
https://ubc.zoom.us/j/63724435704?pwd=QjcvTDdpeCt5RFIySDdHNzEweHVOZz09
Meeting ID: 637 2443 5704
Passcode: 124142
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Event Time:
Thursday, February 10, 2022 | 4:00 pm - 5:00 pm
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2022-02-10T16:00:00
2022-02-10T17:00:00
A new picture of the Cosmos: A two-sheeted, CPT-symmetric universe
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After reviewing some key hints and puzzles from the early universe, I will introduce recent work with Neil Turok suggesting a rigid and predictive new approach to addressing them.
Our universe seems to be dominated by radiation at early times, and positive vacuum energy at late times. Taking the symmetry and analyticity properties of such a universe seriously suggests a picture in which spacetime has two sheets, exchanged by a symmetry that, in turn, selects a preferred (CPT-symmetric) vacuum state for the quantum fields that live on the spacetime. In this picture, the Big Bang may be regarded as a kind of mirror.
This line of thought suggests new explanations for a number of observed properties of the universe, including: its homogeneity, isotropy and flatness; the arrow of time; several properties of the primordial perturbations; and the existence of dark matter (which, in this picture, is one of the three right-handed neutrinos, radiated from the Big Bang like Hawking radiation from a black hole). It also makes several observational predictions that will be tested in the coming decade.
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Thursday, February 10, 2022 | 10:00 am - 11:00 am
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2022-02-10T10:00:00
2022-02-10T11:00:00
Christian Schneider: Exciton-Polaritons and their condensates in microcavities loaded with atomically thin crystals
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https://ubc.zoom.us/j/68470173961?pwd=RTZEak9Pd01WajVOZHN5SW5YZHcyQT09
Meeting ID: 684 7017 3961
Passcode: 113399
Monolayer transition metal dichalcogenides (TMDC) have emerged as a new platform for studies of tightly bound excitons and many-body excitations in ultimately thin materials. Their giant dipole coupling to optical fields makes them very appealing for implementing novel photonic devices, and for fundamental investigations in the framework of cavity quantum electrodynamics [1].
In the regime of strong light-matter coupling between TMDC excitons and microcavity photons , the effect of bosonic condensation of becomes evident in the high-density regime [2]. I will address the question on the emergence of long-range first-order spatial coherence, via interferometric g(1)(t) measurements (Fig. 1c). I will finally discuss the emergence of coherence of exciton-polaritons in a trap at room temperature [3].
Polariton dispersion relation below (0.1 Pth, panel a, excitation laser at 1.671 eV) and above threshold (2Pth, panel b). (c) Real space interference pattern produced in a Michelson interferometer, with a zero delay between the two interfering paths, and one retro-reflected image.
[1] C. Schneider et al. Nature Commun. 9, 2695 (2018).
[2] C. Anton-Solanas, et al. Nature Materials 1-7 (2021).
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