Events List for the Academic Year
Event Time:
Monday, April 3, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-04-03T15:00:00
2023-04-03T16:00:00
Exploring excess variance in LOFAR-EoR using machine learning
Event Information:
Abstract:
The detection of the 21 cm signal from the Epoch of Reionisation (EoR) is challenging due to the strong astrophysical foregrounds, radio frequency interference (RFI), and ionospheric and instrumental effects. Most if not all observations of the 21 cm signal at high redshifts show so-called “excess variance” in their power spectrum, well beyond what would be expected based on the thermal noise limit. Understanding the sources of the excess is crucial for improving upper limits on the EoR signal.
In this talk, I will describe possible sources of the excess variance in LOFAR-EoR and I will introduce a general-purpose data analysis tool, the self-organising attribute maps, to analyse features in residual sky images more efficiently. Also, I will describe how this method can be applied to CHIME data for data quality diagnostics.
Bio:
I am a postdoctoral research fellow at the University of British Columbia. Currently, I am working in 21 cm cosmology on CHIME (The Canadian Hydrogen Intensity Mapping Experiment) data analysis and map-making pipeline. Prior to that, I completed my PhD degree at Kapteyn Institute and Bernoulli Institute in Groningen under the supervision of Prof. dr. Léon Koopmans, Dr. Michael Wilkinson and Dr. André Offringa with the project ''Hunting elusive excess variance in big LOFAR data''.
Learn More:
View Hyoyin's personal webpage here
See Hyoyin speak on "Exploring sources of excess noise in detecting 21cm signal with LOFAR" (Youtube) here
Event Location:
HENN 318
Event Time:
Thursday, March 30, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-30T16:00:00
2023-03-30T17:00:00
Mechanics of diffusion-mediated budding and implications for virus replication and infection
Event Information:
Abstract:
Budding allows virus replication and macromolecular secretion in cells through the formation of a membrane protrusion (bud) that evolves into an envelope. Envelope formation requires the transport of transmembrane (spike) proteins across the membrane, thus, is a diffusion-limited process. This paper proposes a simple model to describe budding in the context of virus replication, discovering size limitations and size-dependent kinetics. The optimal virus size, giving fastest replication, is validated against experiments for Coronavirus, HIV, Flu, and Hepatitis. Moreover, the model can predict the size polydispersity of a virus population, here tested against Coronavirus. Finally, the model is extended to describe infection via endocytosis and membrane fusion.
Bio:
Dr. Mattia Bacca obtained a Bachelor and Master degree in Civil Engineering at the University of Trento (Italy), in 2009. He then obtained a PhD in Structural Engineering at the same university, in 2013. Then he joined the Department of Mechanical Engineering and Materials at the University of California, Santa Barbara (USA) as a Postdoctoral Fellow. Finally, he joined the Department of Mechanical Engineering at the University of British Columbia (Canada), in 2017, as a faculty member. His research is devoted to understanding the biological world through the use of mechanics via the development of mathematical and computational models.
Learn More:
See Mattia's faculty biography and webpage here
Learn more about his research and publications here
Event Location:
HENN 201
Event Time:
Thursday, March 30, 2023 | 10:00 am - 11:00 am
Event Location:
AMPL 311
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2023-03-30T10:00:00
2023-03-30T11:00:00
2D Quantum materials and devices at the atomic scale
Event Information:
Abstract: Material systems, devices, and circuits, based on the manipulation of individual charges, spins, and photons in solid-state platforms are key for quantum technologies. The burgeoning field of quantum two-dimensional (2D) materials presents an emerging opportunity for the development of next-generation quantum technologies, while also pushing the boundaries of fundamental understanding in condensed matter. Our laboratory aims to create quantum functionality in 2D systems by combining fabrication and assembly techniques of 2D layers with atomically precise scanning probe microscopy.
In this talk, I will focus on scanning tunnelling microscopy and spectroscopy experiments aimed at creating novel moiré structures by twisting 2D layers, including the demonstration of reversible local response of domain wall networks in ferroelectric interfaces of marginally twisted WS2 bilayers. I will also discuss our progress in realizing quantum-confined devices in 2D semiconductors.
Speaker Bio: Adina Luican-Mayer is an associate professor and interim Department Chair in the Physics Department at the University of Ottawa. She received her PhD in Physics from Rutgers University (2012). Prior to joining uOttawa, she was the Alexei Abrikosov distinguished postdoctoral fellow at the Center for Nanoscale Materials at Argonne National Laboratory. She is the recipient of uOttawa Faculty of Science Early Career Researcher of the year (2020) and Ontario Early Researcher Award (2021). Her research group focuses on uncovering the novel electronic properties of low-dimensional quantum systems using scanning probe microscopy and supporting spectroscopic techniques.
Event Location:
AMPL 311
Event Time:
Monday, March 27, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-27T15:00:00
2023-03-27T16:00:00
Uncovering the Elusive Origin of Fast Radio Bursts
Event Information:
Abstract:
Upgrades in multiple fast radio burst (FRB) experiments have led to a growing sample of precisely localized events, enabling host galaxy associations and detailed observations of the immediate environments surrounding FRBs. Such observations play a key role in elucidating the stellar populations that give rise to FRB progenitors. Indeed, host galaxy demographics, as well as the spatial offsets of FRBs from their host galaxy centers, can be used to inform progenitor channels. The localizations of two repeating FRBs to dwarf galaxies, their coincidence with persistent radio sources, and their large observed excess dispersion measures (DMs) stand in stark contrast to other localized events, which generally reside in more massive galaxies and exhibit modest excess DMs. Understanding this dichotomy among FRB hosts will provide critical insight into the stellar populations prevalent in FRB host galaxies and hence their likely progenitors.
In this talk, I will review our current knowledge of FRB progenitors based on the properties of a small, but growing sample of host galaxies. I will also outline key follow-up observations that will lend to detailed characterizations of the galactic and local environments of FRBs, thereby shedding light on their progenitor channels.
Bio:
I am a NASA Hubble Einstein Fellow and Radio Astronomer at Northwestern University and a member of the Fast and Fortunate for FRB Follow-up (F4) collaboration. My research focuses on a broad range of astrophysical transients, ranging from fast radio bursts to superluminous supernovae and tidal disruption events. I'm particularly interested in studying the radio properties of these sources to answer key questions about their progenitors, outflows, and environments.
I received my PhD in Astronomy and Astrophysics from Harvard in 2021, and graduated from the University of New Mexico in 2015, where I worked as part of the Long Wavelength Array collaboration.
In my time off, I enjoy playing piano, strength training, carpentry, and delving into Tolkien lore. Though I'm Chicago-bound for the time being, I’m a desert dweller at heart, hailing from the enchanted mountains of Northern New Mexico.
Learn More:
View Tarraneh's personal website here
See her Northwestern webpage here
Event Location:
HENN 318
Event Time:
Thursday, March 23, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-23T16:00:00
2023-03-23T17:00:00
Supporting the integration of computing in physics education
Event Information:
Abstract:
Computing has revolutionized how modern science is done. Modern scientists use computational techniques to reduce mountains of data, to simulate impossible experiments, and to develop intuition about the behavior of complex systems. Much of the research completed by modern scientists would be impossible without the use of computing. And yet, while computing is a crucial tool of practicing scientists, most modern science curricula do not reflect its importance and utility.
In this talk, I will discuss the urgent need to construct such curricula in physics and present research that investigates the challenges at a variety of all scales from the largest (institutional structures) to the smallest (student understanding of a concept). I will discuss how the results of this research can be leveraged to facilitate the computational revolution in science education. This research will help us understand and develop institutional incentives, effective teaching practices, evidence-based course activities, and valid assessment tools. This work has been supported by Michigan State University’s CREATE for STEM Institute, the National Science Foundation, the Norwegian Agency for Quality Assurance in Education (NOKUT), the Norwegian Research Council, and the Thon Foundation.
Bio:
Marcos (Danny) Caballero is an Associate Professor in the Department of Physics and Astronomy and the Department of Computational Mathematics, Science and Engineering. He holds the Lappan-Phillips Chair of Physics Education, co-directs the Physics Education Research Lab, serves as a principal investigator for the Learning Machines Lab, conducts research as part of the newly-founded Computational Education Research Lab, and holds an appointment as research faculty at the University of Oslo’s Center for Computing in Science Education. He helped found the Georgia Tech Physics Education Research group in 2007 and earned the first physics education focused Ph.D. from Georgia Tech in 2011 working on computational modeling instruction and practice. Danny studies how tools and science practices affect student learning in physics and computational science, and the conditions and environments that support or inhibit this learning.
Learn More:
See Danny's website here
Event Location:
HENN 201
Event Time:
Thursday, March 23, 2023 | 10:00 am - 11:00 am
Event Location:
AMPL 311 or watch online
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2023-03-23T10:00:00
2023-03-23T11:00:00
Fracton and Chern-Simons Theory
Event Information:
Abstract: Fracton order describes the peculiar phenomena that point excitations in certain strongly interacting systems either cannot move at all or can only move in a lower dimensional sub-manifold. It has recently been discovered in various lattice models, tensor gauge theories, etc. In this talk, we discuss how another powerful field theory framework -- the 2+1D Chern-Simons (CS) gauge theory -- can be used to provide new insight and explore new possibilities in 3+1D fracton order. 2+1D U(1) gauge theories with a CS term provide a simple and complete characterization of 2+1D Abelian topological orders. To study 3+1D fracton order, we extend the theory by taking the number of component gauge fields to be infinity. In the simplest case of infinite-component CS gauge theory, different components do not couple to each other and the theory describes a decoupled stack of 2+1D fractional Quantum Hall systems with quasi-particles moving only in 2D planes -- hence a fractonic system. More interestingly, we find that when the component gauge fields do couple through the CS term, more varieties of fractonic orders are possible. For example, they may describe foliated fractonic systems which extends the framework found in exactly solvable models. Moreover, we find examples which lie beyond the foliation framework, characterized by 2D excitations of infinite order and braiding statistics that are not strictly local.
Speaker Bio: Xie Chen is a Professor of Theoretical Physics at the California Institute of Technology. Dr. Chen obtained her Ph.D. degree from MIT in 2012 and was a Miller research fellow at the University of California, Berkeley before joining Caltech in 2014. Dr. Chen is a condensed matter theorist studying emergent phenomena in strongly interacting quantum many-body systems. She received the New Horizons in Physics Prize from the Breakthrough Foundation in 2020 and was named a Simons Investigator in 2021.
Event Location:
AMPL 311 or watch online
Event Time:
Tuesday, March 21, 2023 | 9:00 am - 11:30 am
Event Location:
Hennings 318
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2023-03-21T09:00:00
2023-03-21T11:30:00
Dynamics of Transneptunian Objects under the Influence of a Rogue Planet
Event Information:
Over the past two decades, our knowledge of the Solar System's transneptunian region (often called the Kuiper Belt) has been gradually increasing. Observational surveys have greatly expand the inventory of TNOs, which are distant icy bodies thought to be relics from the giant planet formation and migration era. As more intricate details are unveiled in the TNO orbital and physical properties, several aspects are thought to be tightly linked to the Solar System's early formation.
In the main Kuiper Belt region, a complex bimodal inclination structure is present, leading to the common assertion that current TNOs may have accreted in different regions of the protoplanetary disk. The cold population likely formed in-situ and had not experienced significant orbital excitation from planetary perturbations, whereas the hot (high
inclination) population likely formed closer to the Sun and was implanted during the phase of giant planet migration. To study this blended inclination structure with better clarity, I develop an improved semi-analytical method to computer TNO `free' inclinations, which are well conserved and thus better represent the primordial inclination profile. This study shows that a 4° cut in free inclination (as opposed to the time-varying ecliptic inclination) produces a more reliable separation of the two population.
In the distant Kuiper Belt (semimajor axes beyond 50 au), several striking features seem to challenge our previous understanding of the early Solar System's dynamical history: 1) a very large population of objects in distant mean-motion resonances with Neptune, 2) a substantial detached population that are not dynamically coupled with Neptune's effects, and 3) the existence of three very large perihelion objects, represented by Sedna. No published planet formation and migration models simultaneously explain all three features and match de-biased observations.
I demonstrated in this thesis, that a super-Earth-mass planet temporarily present in the Solar System on a Neptune crossing orbit (referred to as a ”Rogue Planet“), is able to create all these structures in the distant Kuiper Belt. Such a planet would have formed in the giant planet region, and gotten scattered on a highly-eccentric orbit with a few hundred au semimajor axis with a typical lifetime of
100 Myr. Additionally, I showed this transient planet would not have heated the cold belt's very low free inclinations to larger than observed. Both the structures in the distant belt and the existence of an unheated cold belt provide constraints to narrow down the mass and possible dynamical histories the rogue might took.
Event Location:
Hennings 318
Event Time:
Monday, March 20, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-20T15:00:00
2023-03-20T16:00:00
Illuminating Dark Halos with Gravitational Lensing
Event Information:
Abstract:
Gravitational lensing is a powerful cosmic tool for exploring a wide range of astrophysical phenomena including understanding how ordinary and dark matter couple and finding the earliest galaxies and stars. Using Convolutional Neural Networks to sift through legacy imaging data-sets, the AGEL survey confirms about 100 strong gravitational lenses that identify halos spanning a wide range in total mass and cosmological distance. I provide an overview of the AGEL survey and describe AGEL projects based on observations from the Hubble Space Telescope, Keck Observatory, and the Very Large Telescope.
Bio:
I joined the UNSW faculty in 2017 and have been a professional astronomer for 20+ years. I also was a professor at the University of Zürich and Texas A&M University. I received my PhD in Astronomy & Astrophysics from the University of California, Santa Cruz and I held postdoctoral fellowships at the Harvard-Smithsonian Center for Astrophysics, Leiden Observatory, and ETH Zürich. I have given 180+ presentations at universities and conferences around the world
Learn More:
See Kim-Vy's faculty webpage here
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-16T16:00:00
2023-03-16T17:00:00
Biophysics in latent space
Event Information:
Abstract:
Many phenomena in biology are considered too complicated or too contingent to be captured by predictive theories similar to what is done in physics. But complex systems theory has taught us that simple, higher level laws with few effective parameters can emerge from the interaction of small scale components. As biology is becoming more and more quantitative, one can use a combination of first-principle theoretical modelling with simple machine learning techniques to build accurate and tractable theories of biological dynamics. Those dynamics can often be best understood in (abstract) latent spaces, giving « physics-like » intuition.
I will illustrate the power of such approaches on a couple of biological examples, with a special focus on the dynamics of the adaptive immune system (T cells response). Our approach leads to applications in cancer immunotherapy that I will briefly describe.
Bio:
Paul François is a Professor of Bioinformatics at the Université de Montréal and an associate member of MILA, an AI research institute in Quebec. He earned his PhD from Université Paris in 2005, and today is a leading expert in theoretical and computational biophysics. His team applies machine learning approaches to explore an array of biophysics topics, including systems biology, developmental biology, evolution, and quantitative immunology. Among other accolades, Prof. François was awarded the Rutherford Memorial Medal in Physics by the Royal Society of Canada in 2019 and the CAP Herzberg Medal in 2017.
Learn More:
See Paul's faculty research page here
See the François group website here
Event Location:
HENN 201
Event Time:
Thursday, March 16, 2023 | 2:00 pm - 3:00 pm
Event Location:
HENN 318
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2023-03-16T14:00:00
2023-03-16T15:00:00
Classifying topological quantum pumps
Event Information:
Abstract:
In his seminal work, Thouless considered the evolution of a non-interacting electron gas under periodic driving and showed that the charge transported in a cycle is quantized provided the Fermi energy remains in a spectral gap throughout the evolution. In this talk, we will consider periodic transformations of states of locally interacting matter, which are both invariant under a compact group G and short range entangled. I will explain that a quantized $G$-charge is pumped during each cycle. Moreover, the pumping is stable under deformations of the loops, and two loops pumping the same charge can be deformed into each other. I will further relate this work to the classification of symmetry protected states.
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-16T11:00:00
2023-03-16T12:00:00
Structuring light to reveal the invisible
Event Information:
Abstract:
From quantum physics to cosmology, researchers aim to “see” things which are typically invisible – be it the entanglement of two particles or infrared signatures from space. In these and various other fields, we are confronted by a common challenge: What we can see with our own eyes or observe using standard optical imaging systems is limited to a small fraction of the information that the detected light actually carries. Two-dimensional (2D), flat images, such as a photo, only reveal the intensity and visible color of the light coming to us from an optical scene. However, light contains a wealth of information on the three-dimensional (3D) position, angle of incidence, spectral context, amplitude, phase, polarization, optical angular momenta, coherence, amongst others. In fact, if light interacts with media, nature will give us structured light that is spatially varying in the named properties in a fashion that depends on the interaction. In this talk, I will present how we can use these kinds of structured light fields to extract information from an optical scene and, vice versa, how structured light can serve as an excitation or probing tool to gain access to usually invisible information. In this context, we will explore “optical vortices” in phase and polarization, their generation, and application. Moreover, we will gain insights into the nanoscale features of structured light and its leading role for next-generation imaging techniques.
Bio:
Eileen Otte is a postdoctoral researcher in Prof. Mark Brongersma’s group at Stanford University, USA. After her undergraduate studies and completing her Master degree with distinction, she specialized on structured singular light in her PhD studies. She performed her research at the University of Muenster (WWU), Germany, as well as the University of Witwatersrand, South Africa, under the supervision of Prof. Dr. Cornelia Denz and Prof. Dr. Andrew Forbes. In 2019 she finished her PhD, honored with "summa cum laude" and the WWU Dissertation Award in Physics, and published in the Springer Theses series. Further, she received the Research Award 2020 of the Industrial Club Duesseldorf and was accepted as a junior class member of the NRW Academy of Sciences, Humanities, and the Arts. After her PhD, Eileen performed research on complex topological structures in light and light-matter-interaction, including new structured-light-based sensing approaches. Since 2021, at Stanford and in collaboration with the Center for Soft Nanoscience (WWU), she concentrates on imaging nano-scale emitters using metasurfaces. Supporting her research, Eileen was awarded the GLAM fellowship (Stanford University) as well as the PRIME fellowship (DAAD, Germany).
Learn More:
See article on Eileen's research and funding award from the DAAD program here
Event Location:
HENN 318
Event Time:
Thursday, March 16, 2023 | 10:00 am - 11:00 am
Event Location:
AMPL 311
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2023-03-16T10:00:00
2023-03-16T11:00:00
Semiconductor Quantum Dots
Event Information:
Abstract: Semiconductor nanostructures with low dimensionality like quantum dots are one the best attractive solutions for achieving high performance photonic devices. When one or more spatial dimensions of the nanocrystal approach the de Broglie wavelength, nanoscale size effects create a spatial quantization of carriers along with various other phenomena based on quantum mechanics. Thanks to their compactness, great thermal stability and large reflection immunity, semiconductor quantum dot lasers are very promising candidates for low energy consumption and isolation free photonic integrated circuits. When directly grown on silicon, they even show a four-wave mixing efficiency much superior compared to the conventional quantum well devices. This remarkable result paves the way for achieving high-efficiency frequency comb generation from a photonic chip. Quantum dot lasers also exhibit a strong potential for applications in optical routing and optical atomic clock. Last but not least, a quantum dot single photon source is a building block in secure communications, and therefore can be applied to quantum information processing for applications such as quantum computers. This lecture will review the recent findings and prospects on nanostructure based light emitters made with quantum-dot technology. Many applications ranging from silicon-based integrated solutions to quantum information systems will be presented. In addition, the lecture will highlight the importance of nanotechnologies on industry and society especially for shaping the future information and communication society.
Speaker Bio: Frédéric Grillot is currently a Full Professor at Télécom Paris (France) and a Research Professor at the University of New-Mexico (USA). His research interests include, but are not limited to, advanced quantum confined devices using III-V compound semiconductors, quantum dots quantum dashes, light-emitters based on intersubband transitions, non-classical light, nonlinear dynamics and optical chaos in semiconductor lasers systems as well as microwave and silicon photonics applications.
Professor Grillot has made outstanding technical contributions in photonics and optical communications. He has intensively contributed to the development of quantum dot devices enabling their utilization as future active devices with superior performance. In particular, his recent achievements on epitaxial quantum dot lasers on silicon are crucial for the development of isolation-free integrated technologies. Among his major achievements, he also reported the first private optical communication using mid-infrared chaotic light, giant pulses emission in quantum cascade devices as well as multigigabits operation in the thermal atmospheric window with unipolar quantum optoelectronics. Overall, his research is a strong input to the advancement of science and to the emerging practical applications in computer and quantum technologies, as well as in more traditional areas such as optical communications.
Professor Grillot strongly contributes to promote and support the development of the general optics community. He has served diligently and successfully Optica in particular as an Associate Editor of Optics Express, now as a Deputy Editor since September 2022. As of now, he has published more than 130 journal articles, 3 book chapters, and delivered many invited talks in major international conferences and workshops. Frédéric Grillot is also a Fellow Member of the SPIE as well as a Senior Member of Optica and the IEEE Photonics Society. In 2022, he received the IEEE Photonics Society Distinguished Lecturer Award which honors excellent speakers who have made technical, industrial or entrepreneurial contributions to the field of photonics.
Jointly organized with the IEEE Vancouver Joint Communications Chapter
Event Location:
AMPL 311
Event Time:
Monday, March 13, 2023 | 3:00 pm - 4:00 pm
Event Location:
HENN 318
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2023-03-13T15:00:00
2023-03-13T16:00:00
The Dragonfly Spectral Line Mapper: New eyes to reveal the faintest and largest structures in the universe
Event Information:
Abstract:
The majority of baryons in the universe exist outside galaxies, in the circumgalactic (CGM) and intergalactic medium (IGM). The properties of these structures are important to understand as the material they hold is required to fuel ongoing star formation in galaxies. The process of how the gas in the CGM gets into galaxies (and is blown back out through galactic feedback) is still debated, though – in fact, the total mass of the CGM of galaxies is still unknown. This mystery remains due to the near invisibility of the CGM and IGM.
In this talk, I will describe an upcoming upgrade to the Dragonfly Telephoto Array that implements ultra-narrow bandpass imaging capability on the telescope which will enable it to directly image the CGM of local galaxies. I will present the results from a pathfinder version of the upgraded Dragonfly and the plans for the full upgrade, the Dragonfly Spectral Line Mapper, which is currently under construction (with first light expected within a month!).
Bio:
Deborah uses a combination of instrumentation, observation and theoretical astrophysics to investigate galaxy formation and evolution, and the role of dark matter in the universe. She started working with and building instrumentation for the Dragonfly Telephoto Array during her PhD at the University of Toronto and the Dunlap Institute. After graduating in 2021, she has continued working with Dragonfly as a Herzberg Instrument Science Fellow at the NRC Herzberg Astronomy & Astrophysics Research Centre in Victoria, BC, Canada.
Learn More:
See Deborah's personal webpage here
See her National Research council of Canada webpage here
Event Location:
HENN 318
Event Time:
Monday, March 13, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-13T11:00:00
2023-03-13T12:00:00
Quantum devices and the frontier of many-body physics
Event Information:
Abstract:
I will make the case that new possibilities for the precise control and measurement of quantum devices have led to a quiet revolution in the way we think about physical systems, beyond the headline-grabbing promise of quantum computers. I will begin by explaining how present-day quantum devices, from systems of ultracold atoms to chains of superconducting qubits, have given a new impetus to the venerable theory of hydrodynamics, realizing regimes of non-equilibrium dynamics that were completely unanticipated even a few decades ago. I will then discuss how the age of highly controllable quantum devices calls for updated notions of “quantumness” of physical states. Traditionally, this tends to be quantified in terms of entanglement. I will argue that less well-studied notions of quantumness, such as quantum contextuality, are better suited for understanding how to prepare complicated quantum states and use them to accomplish classically difficult tasks.
Bio:
I am a theoretical physicist with broad interests in statistical physics and emergent phenomena, and a particular focus on how these concepts apply to quantum many-body systems.
At PCTS, I am exploring a cluster of interrelated questions around (i) delineating the boundary between chaos and integrability for many-body systems (ii) using quantum computational complexity as a probe for quantum dynamics (iii) classifying phases of matter by their quantum information content.
Learn More:
See Vir's Princeton webpage here
Event Location:
HENN 318
Event Time:
Thursday, March 9, 2023 | 4:00 pm - 5:00 pm
Event Location:
HENN 201
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2023-03-09T16:00:00
2023-03-09T17:00:00
Improving Student Learning: The Dual Roles of Conceptual Understanding and Reasoning Ability
Event Information:
Abstract:
Why do students make errors on physics problems? Errors that directly contradict what they have been taught? Errors that don’t arise from the failure to remember the correct formula? For the past several decades, physics education researchers have focused on one compelling explanation: students arrive in the classroom with pre-formed ideas about how the world works. Even though they may blend these ideas with those presented in formal instruction, the prior conceptions often win out. According to these accounts, students’ prior knowledge has been built through rational, if imperfect, processes of observation and analysis, and any new or different ideas presented in the classroom must likewise be built, not simply received.
Figuring out what ideas students bring with them to the classroom, and how to take them into account, has proven to be a complex, multi-faceted program of research that has significantly influenced physics teaching. However, it is not always the case that students produce incorrect answers through logical inferences based on incorrect or inappropriate premises – often they don’t know why they chose a particular answer, just that it seems right. “Dual-process” theories suggest that their answers might not be based on so-called “slow” thinking, which is deliberate and laborious. Instead they might be based on so-called “fast” thinking, which is automatic and effortless. The basic idea is that students immediately and effortlessly form a first-impression of a physics problem. If this impression is found to be satisfactory, it will be adopted. Otherwise, a deliberate and analytical process ensues. It is believed that this sequence cannot be “turned off.” That is, a first impression will always be formed. If it is attractive, and the benefits of engaging in more effortful thinking are not obvious, then a student may answer incorrectly, masking their conceptual knowledge.
In this talk, I will discuss recent efforts to improve both conceptual understanding and reasoning skills. Examples will be chosen from first-year university-level physics.
Bio:
Paula R.L. Heron is a Professor of Physics at the University of Washington. She holds a Ph.D. in physics from the University of Western Ontario. Dr. Heron’s research focuses on the development of conceptual understanding and reasoning skills. She has given numerous invited talks at international meetings and in university science departments. Dr. Heron is co-Founder and co-Chair of the biannual “Foundations and Frontiers in Physics Education Research” conference series, the premier venue for physics education researchers in North America. She has held leadership roles in the American Physical Society (APS), the American Association of Physics Teachers (AAPT), and the European Physics Education Research Group (GIREP). She served on the National Research Council committee on the status and outlook for undergraduate physics education and co-chaired an APS/AAPT joint task force that produced the report Phys21: Preparing Physics Students for 21st Century Careers. She also serves as an Associate Editor of Physical Review – PER. She is a Fellow of the APS, a co-recipient of the APS Education award with colleagues Peter Shaffer and Lillian McDermott, and recipient of the Homer Dodge Citation for Outstanding Service to the AAPT. Dr. Heron is a co-author on the upcoming 2nd Edition of Tutorials in Introductory Physics, a set of influential instructional materials.
Learn More:
See Paula's faculty webpage here
See her ResearchGate page here
Event Location:
HENN 201
Event Time:
Thursday, March 9, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-09T11:00:00
2023-03-09T12:00:00
In pursuit of entanglement: XXZ interactions for spin-squeezing in atomic and solid-state spin ensembles
Event Information:
Abstract:
Controlling many-body entanglement promises to yield both fundamental insights and practical advances. In particular, generating squeezed states for entanglement-enhanced metrology is an important near-term application of quantum systems. In past work, squeezing has been achieved in a clean, controlled setting using all-to-all Ising interactions between ultracold atoms in an optical cavity. By contrast, optically-addressable spin defects in solids, such as the nitrogen-vacancy center in diamond, are far more practical and versatile sensors, but it is not known whether the requisite ingredients for generating and detecting squeezing are attainable in this platform.
In this talk, I will discuss two complementary approaches for generating squeezed states using XXZ interactions. The first approach centers around a cavity QED platform designed to realize programmable, nonlocal spin-spin couplings. Specifically, we implement an all-to-all XXZ Hamiltonian with tunable anisotropy, strength, and sign. Images of the resulting magnetization dynamics show that XXZ interactions protect spin coherence against spatial inhomogeneities, which may enhance the robustness of future spin-squeezing protocols.
The robustness of the XXZ model against disorder opens the door to squeezing via long-range dipolar interactions within an ensemble of spin defects in diamond, for which we identify and achieve the key required ingredients: (i) a theory that elucidates if and how power-law XXZ interactions generate squeezing; (ii) a two-dimensional ensemble of strongly-interacting, optically-polarizable spins; (iii) methods for detecting squeezing despite significant technical noise.
Event Location:
HENN 318
Event Time:
Wednesday, March 8, 2023 | 4:00 pm - 5:00 pm
Event Location:
Henn 318
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2023-03-08T16:00:00
2023-03-08T17:00:00
Special Gravity Seminar: The LIGO-Virgo search for gravitational waves associated with Fast Radio Bursts Detected by CHIME/FRB
Event Information:
TALK RECORDING AVAILABLE AT: https://drive.google.com/file/d/1DJ1iAdZ5QPBlQsxkCxyLmdvBqusGGbv7/view?usp=share_link
Abstract:
I will present the results from the search for gravitational waves associated with Fast-Radio Bursts (FRBs) detected by the CHIME/FRB experiment during the LIGO-Virgo Observing Run O3a, from 1 April 2019 15:00 UTC - 1 October 2019 15:00 UTC. We have used both a generic gravitational wave transient search and a modelled search targeting coalescing binary systems. Several source types and morphologies were used during the searches. Assuming inferred FRB distances, we compare lower bounds on the GW detection distances and present upper limits on the possible energies emitted by gravitational waves for a range of transient models. I will also describe the status of the LIGO-Virgo-Kagra O3b search for gravitational wave counterparts to CHIME/FRB data. Finally, I will discuss preparations for the O4 LIGO-Virgo-Kagra Observation runs and the constraints that could be set by future joint GW/FRB searches.
Event Location:
Henn 318
Event Time:
Wednesday, March 8, 2023 | 12:00 pm - 1:00 pm
Event Location:
HENN 318
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2023-03-08T12:00:00
2023-03-08T13:00:00
Development of an EDI.I Competency Framework for Engineering Programs
Event Information:
How are concepts of equity, diversity, inclusion and Indigeneity (EDI.I) taught and assessed in applied sciences?
Why is the teaching of these concepts important for engineers and scientists and how can competency level be meaningfully assessed?
Come to listen, learn, and discuss these questions and more in this month’s EDI in PHAS Journal Club! Jessica Wolf is a 2nd year MASc student in Mechanical Engineering and will lead our discussion on her work to develop an Equity Competency Model for UBC’s Faculty of Applied Sciences. Jessica’s work is inspired by the Valley Competencies (pp. 8-16
of linked journal article) and looks to translate such frameworks into applied sciences.
Coffee and Cookies to be provided!
Event Location:
HENN 318
Event Time:
Tuesday, March 7, 2023 | 12:30 pm - 1:30 pm
Event Location:
HENN 318
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2023-03-07T12:30:00
2023-03-07T13:30:00
X-Ray Polarization Observations of Stellar Mass Black Holes in X-Ray Binaries with the IXPE and XL-Calibur Experiments
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Abstract:
The Imaging X-Ray Polarimetry Explorer (IXPE) mission is a satellite borne observatory that measures the linear polarization of the 2-8 keV X-rays from cosmic sources. I discuss here some of the recent results obtained with IXPE for stellar mass black holes. I will furthermore give a brief description of several balloon borne X-ray and gamma ray missions on which I am working, including the hard X-ray polarimetry mission XL-Calibur, the Dilution Refrigerator and Transition Edge Sensor array test flight DR. TES, and the pointed 511 keV gamma ray mission 511-CAM.
Bio:
Professor Krawczynski works on experimental and theoretical astroparticle physics. His work aims at revealing the inner workings of astrophysical black holes, and using black hole and neutron star observations for testing the theory of General Relativity and the Standard Model of Particle Physics in regimes not accessible in terrestrial laboratories.
Learn More:
See Henric's Faculty webpage at the Washington University in St. Louis here
Event Location:
HENN 318
Event Time:
Tuesday, March 7, 2023 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2023-03-07T11:00:00
2023-03-07T12:00:00
Echos of the Early Universe in Axion Haloscopes
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Abstract:
The coming decade will bring dramatic improvement in the axion dark-matter program as new experimental designs move beyond the proof of principle stage. In this talk I will outline two signals beyond dark matter that these instruments could discover. The first is a population of relativistic axions that were produced in the early universe and persist as a residual Cosmic axion Background (CaB). The second is high-frequency gravitational waves; I will outline how exploiting an analogy between axion and gravitational-wave electrodynamics allows for axion haloscopes to be converted into gravitational-wave telescopes.
Bio:
Nicholas Rodd grew up in Melbourne, Australia, and completed his undergraduate degrees in Science and Law at Melbourne University. He then moved to MIT, where he obtained his PhD in 2018 under the supervision of Tracy Slatyer, focusing on the indirect detection of dark matter. After MIT, Nicholas went to U.C. Berkeley as a Miller Fellow for three years, before joining the theory division at CERN in 2021, where he is currently a Staff Member.
Learn More:
View Nicholas' webpage here
See his Youtube video on the Cosmic Axion Background here
Event Location:
HENN 318