Events List for the Academic Year
Event Time:
Thursday, July 17, 2025 | 10:00 am - 11:00 am
Event Location:
BRIM 311
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2025-07-17T10:00:00
2025-07-17T11:00:00
The Strange Universe of Quantum Phases Driven by Interplay between Multipoles and Conduction Electrons
Event Information:
Multipolar moments embedded in a metallic setting paves a new route to extend the landscape of novel quantum phenomena beyond the spin-only paradigm [1]. A model material platform for exploring multipolar physics is the cubic heavy-fermion system PrTr_2Al_20 (Tr = Ti, V). This system features a nonmagnetic ground state in which the magnetic dipolar moment (spin) is absent, but higher-rank multipolar moments (quadrupoles and octupoles) are active [2]. The Kondo entanglement of these local multipolar moments with conduction electrons results in a rich phase diagram comprising multipolar orders, non-Fermi liquid (NFL) phase, and exotic superconductivity [2-5]. In this talk, I will present our experimental investigation into the multipolar ordered phases multipolar quantum criticality and novel superconductivity in PrTr_2Al_20, which contrast sharply from those in the familiar magnetic settings. References [1] S. Paschen and Q. Si, Nat. Rev. Phys. 3, 9-26 (2021) [2] A. Sakai and S. Nakatsuji, J. Phys. Soc. Jpn. 80, 063701 (2011) [3] K. Matsubayashi, T. Tanaka, A. Sakai et al., Phys. Rev. Letts. 109, 187004 (2012) [4] M. Fu, A. Sakai, N, Sogabe et al., J. Phys. Soc. Jpn. 89, 013704 (2020) [5] A. Sakai, Y. Matsumoto, M. Fu et al., Nat. Commun 16, 2114 (2025)
Speaker Bio: Dr. Mingxuan Fu received her undergraduate degree in Physics from the University of Toronto in 2010 and earned her PhD in Experimental Condensed Matter Physics from McMaster University in 2015. She subsequently held a joint postdoctoral position with Professor Collin Broholm at Johns Hopkins University and the NIST Center for Neutron Research, followed by a NSERC postdoctoral fellowship under Professor Stephen Julian at the University of Toronto (2015–2019). In 2019, Dr. Fu joined the University of Tokyo as a JSPS Fellow and is currently a Project Assistant Professor in the Department of Physics. She is a member of Professor Satoru Nakatsuji’s research group. Her research experiences encompass several central themes in quantum materials, including quantum critical phenomena and exotic superconductivity in strongly correlated electron systems, frustrated quantum magnetism, and topological materials, and her current focus is on multipolar-driven quantum phenomena and functional topological antiferromagnets.
Event Location:
BRIM 311
Event Time:
Thursday, June 19, 2025 | 6:00 pm - 7:30 pm
Event Location:
Vancouver Public Library - Central Branch (Alice MacKay Room, Lower Level)
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2025-06-19T18:00:00
2025-06-19T19:30:00
How the Universe Works: An Introduction to Galactic Radio Astronomy
Event Information:
Curious about how the universe actually works? Join the experts from UBC’s Department of Physics and Astronomy to find out fun facts about everything from the Milky Way to radio waves in this new, accessible science series: How the Universe Works! All are welcome!
Abstract:
Imagine that you look up on a dark clear night, seeing countless stars scattered across the sky, divided by the hazy band of the Milky Way—our Galaxy. The haziness of the Galactic Plane is caused by vast clouds of dust lining the Galactic disk, which obscure much of the Galaxy from our sight. But what if we could see beyond the dust, revealing the hidden structures and objects that share our cosmic home? This is where Galactic radio astronomy truly shines, allowing us to peer through the darkness and uncover the Milky Way’s secrets.
In this talk, we’ll step beyond the limits of optical astronomy and into the invisible world of radio waves, mapping our Galaxy in a whole new way. From the birth of radio astronomy to the frontiers of modern research, we’ll explore how these maps not only help us understand the Milky Way but also allow us to remove it from our view—clearing the way to see the universe beyond.
Bio:
Dr. Thomas J. Rennie is a postdoctoral researcher at the University of British Columbia, where he specializes in analyzing and interpreting radio maps of the Milky Way. After obtaining his Ph.D., Dr. Rennie joined UBC to work on the Canadian Galactic Emission Mapper (CGEM) project, which focuses on a new telescope being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. CGEM maps will play a key role in a global effort to further our understanding of our Galaxy and to look deeper and reveal the echo of the Big Bang (the Cosmic Microwave Background, or CMB) and probe the very earliest moments in the history of the universe.
Learn More:
About the Canadian Galactic Emission Mapper (CGEM) project: https://cgem.ubc.ca/
About the Dominion Radio Astrophysics Observatory (DRAO): https://nrc.canada.ca/en/research-development/nrc-facilities/dominion-radio-astrophysical-observatory-research-facility
About the "Big Bang": https://science.nasa.gov/universe/the-big-bang/
About the Cosmic Microwave Background: https://lambda.gsfc.nasa.gov/education/graphic_history/microwaves.html
About Thomas Rennie: https://tjrennie.github.io/index.html
Event Location:
Vancouver Public Library - Central Branch (Alice MacKay Room, Lower Level)
Event Time:
Thursday, June 5, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-06-05T11:00:00
2025-06-05T12:00:00
Quantum chaotic systems and black holes: puzzles and lessons from an information-theoretic perspective
Event Information:
Abstract:
Most systems in nature are chaotic many-body systems, and show the universal phenomenon of thermalization. While some "coarse-grained" aspects of thermalization are familiar from our everyday lives, quantum information theory provides a window into more fine-grained universal properties of thermalizing systems. I will discuss examples from my work of insights and surprises that come from asking operationally motivated questions about quantum chaotic systems. I will also introduce approaches for addressing the elusive question of how and why universality emerges across systems with widely differing microscopic dynamics. Remarkably, there is a lot of evidence that black holes in their fundamental description can be seen as examples of highly chaotic quantum many-body systems. While this principle allows us to make predictions for black holes based on properties of quantum chaotic systems, such predictions are often in conflict with the semiclassical description of gravity in a regime where it should naively be valid. I will discuss a proposal for using computational complexity to understand the subtle relation between the semiclassical and fundamental descriptions of the black hole interior.
Bio:
Shreya Vardhan is a postdoctoral fellow at the Institute for Quantum Information and Matter at Caltech. She received her Ph.D. at MIT in 2022, and was a postdoc at the Stanford Institute for Theoretical Physics from 2022 to April 2025. Shreya's research interests lie at the intersection of quantum information theory, quantum many-body physics, and quantum gravity. Her work has included topics in entanglement dynamics, the black hole information loss paradox, hydrodynamics, and information-theoretic properties of states in conformal field theories. One of her key goals in the next few years will be to better understand the interplay between the dynamics of information and the flow of energy and other conserved quantities in many-body systems. Another important goal will be to test and develop recent ideas about the role of complexity in black hole physics in the context of more realistic gravity models.
Learn More:
Watch her videos (there are more on Youtube):
BHI Colloquium Talks | 11.18.2024 | Shreya Vardhan (Stanford University): https://www.youtube.com/watch?v=uo8OmGoz8VY
Shreya Vardhan (Stanford University): Entanglement dynamics from universal low-lying modes: https://www.youtube.com/watch?v=kYHd7MWatiY
Mixed-state entanglement and information recovery in evaporating black holes: https://www.youtube.com/watch?v=ItevkmLw7rE
Read her thesis: Chaos and Thermalization in Quantum Many-Body Systems and Gravity: https://dspace.mit.edu/bitstream/handle/1721.1/150679/vardhan-vardhan-phd-physics-2022-thesis.pdf?sequence=1&isAllowed=y
Event Location:
HENN 318
Event Time:
Monday, June 2, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-06-02T11:00:00
2025-06-02T12:00:00
A many-body physics perspective on quantum error correction
Event Information:
Abstract:
Quantum computers hold transformative promise for both scientific and real-world applications, but their practical operation is often hindered by errors and decoherence. In this talk, I will discuss how the co-design of quantum hardware and algorithms creates new opportunities with today’s non-fault-tolerant devices. First, focusing on one such computational platform—neutral atom arrays—I will explore the design of a topological qubit and demonstrate how it enables robust quantum information processing. Then, inspired by recent advances in many-body quantum dynamics, I will examine certain fundamentally out-of-equilibrium dynamical critical phenomena in quantum and classical systems. I will show how these phenomena can be harnessed for quantum state preparation in both analog systems and quantum circuits incorporating measurement and feedback, offering a scalable route to passive quantum error correction.Bio:
Rhine Samajdar is a Princeton Quantum Initiative Postdoctoral Fellow in the Department of Physics and PCTS at Princeton University. His research interests lie at the interface of theoretical quantum information science, condensed matter physics, and atomic, molecular, and optical physics. Prior to joining Princeton, he obtained his PhD in Physics from Harvard University in 2022 working with Subir Sachdev. His work has demonstrated how quantum computation can be used to realize, probe, and control novel phases of quantum matter, providing new insights into topological architectures, quantum algorithms, and nonequilibrium dynamics.
Learn More:
About Rhine's research: https://pcts.princeton.edu/people/rhine-samajdar
Event Location:
HENN 318
Event Time:
Friday, May 30, 2025 | 12:00 pm - 2:30 pm
Event Location:
HEBB 116
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2025-05-30T12:00:00
2025-05-30T14:30:00
Searching for Millisecond and Slow Pulsars with CHIME
Event Information:
Abstract:Born in core-collapse supernovae, pulsars are highly-magnetized, spinning neutron stars, which emit highly directional electromagnetic radiation in beams above their magnetic poles. This produces a lighthouse effect: we see a pulse of radiation as the beam crosses our line-of-sight, repeating with each rotation of the neutron star.
These periodic pulses can reveal a wealth of information about the neutron star, its environment, material the signal encounters on its way to Earth, and even the behaviour of spacetime. There are many remaining mysteries about these objects and, thus far, we have only discovered a small fraction of them. New surveys to discover more pulsars, therefore, have great scientific potential.In this thesis I use the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope to perform two distinct pulsar surveys on the same small patch of sky. These serve as pilots for larger-scale surveys over the entire CHIME-visible sky.
The CHIME All-sky Multi-day Pulsar Stack Search (CHAMPSS) survey uses the data stream from the CHIME/FRB instrument, taking data from the whole Northern sky as it passes overhead and combining data from multiple days to detect fainter pulsars. However, it is not sensitive to the fastest pulsars with periods below ∼ 10 ms.
The other survey uses the CHIME/Pulsar system to take multiple observations of the same point on the sky, correcting for different amounts of material between the Earth and potential pulsars. This scheme lets it detect the fastest pulsars further out into the Galaxy. However, the CHIME/Pulsar survey does not combine multiple days’ data and so will not detect the faintest pulsars found by CHAMPSS. The two surveys are thus sensitive to different, but overlapping, sections of the pulsar population, and further demonstrate the collaborative nature of CHIME which allows multiple experiments to run simultaneously.
In this thesis I describe the software pipeline for each survey. The CHIME All-sky Multi-day Pulsar Stack Search (CHAMPSS) pipeline I developed as part of a group; the CHIME/Pulsar pipeline was an individual project. I also present PSR J2108+5001, a newly discovered pulsar in the pilot survey area, and J1629+4636, J2100+4711, J2151+5128, and J2319+4919 which were discovered during a subsequent CHAMPSS commissioning survey.
Event Location:
HEBB 116
Event Time:
Thursday, May 29, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-05-29T11:00:00
2025-05-29T12:00:00
Condensed matter theory in the quantum information era
Event Information:
Abstract:
The rapid development of new experimental platforms enables the study of quantum many-body systems using both existing materials and synthetic matter. This progress has spurred the search for novel phenomena in regimes beyond traditional near-equilibrium settings, two aspects of which will be explored in this talk. We will first discover that kinetic constraints and symmetries can be utilized to halt quantum thermalization, and to even shield a system from decohering. These striking outcomes emerge via the mechanism of Hilbert space fragmentation--a phenomenon since realized experimentally in various platforms. We will then explore the physics of many-body ground states and show how even “weak” measurements can tame the rigidly universal properties emerging at quantum critical points. Drawing inspiration from quantum information, this discovery informs the design of optimally resilient teleportation protocols that transfer critical wavefunctions between distant labs. Finally, we will discuss open questions and related ideas in the field.
Bio:
I am currently a postdoctoral fellow at the California Institute of Technology (Caltech), where I hold a Burke Institute Prize Fellowship. I completed undergraduate degrees in both Physics and Mathematics in Zaragoza, Spain. After finishing a master's program in Theoretical and Mathematical Physics in Munich---with a thesis on the use of variational methods for lattice gauge theories at the Max Planck Institute for Quantum Optics---I pursued a PhD at the Technical University of Munich (TUM) under the supervision of Prof. Pollmann, supported by a "la Caixa" fellowship. My doctoral research led to the discovery of Hilbert space fragmentation, an ergodicity-breaking mechanism that deepens our understanding of the role of symmetries in the dynamics of many-body systems.
As a postdoctoral fellow at Caltech, I have developed a research program focused on various aspects of quantum many-body physics in the presence of measurements and decoherence---a relevant area to emerging quantum technologies. My recent work includes the demonstration and quantification of entanglement generation in open (mixed-state) systems, the characterization of non-Abelian topological order under decoherence, and the identification of novel phenomena induced by quantum measurements.
Learn More:
About Pablo: https://www.pma.caltech.edu/people/pablo-sala
Event Location:
HENN 318
Event Time:
Wednesday, May 28, 2025 | 2:00 pm - 3:00 pm
Event Location:
Via zoom
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2025-05-28T14:00:00
2025-05-28T15:00:00
Toward the generation of high-energy temporal solitons in a free-space enhancement cavity
Event Information:
Abstract:
A soliton is a wave packet that retains its shape as it propagates due to a balance between the dispersion and non-linear response of a medium. These wave packets have garnered interest in the areas of frequency generation and ultrafast laser mode-locking due to their stability and self-reinforcing properties. Here, we describe the development of a system designed to be capable of generating such a wave packet in a free-space ultrafast enhancement cavity. This consists of three main parts: a homemade ultrafast fibre laser system, the enhancement cavity itself, and a frequency locking system to stabilize the laser output relative to the cavity resonances. The laser is capable of outputting up to 4 W average power and pulse durations on the order of 200 fs, while the overall system has so far demonstrated an average power enhancement factor of 204, corresponding to a potential intracavity average power of more than 800 W. This demonstrates the potential of this platform to support soliton generation, allowing one to study soliton dynamics or improve upon current intracavity non-linear frequency conversion processes.
Event Location:
Via zoom
Event Time:
Tuesday, May 27, 2025 | 2:00 pm - 3:00 pm
Event Location:
This seminar will only be available on zoom
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2025-05-27T14:00:00
2025-05-27T15:00:00
Building the world’s first open-source quantum computer
Event Information:
Abstract:
As quantum computers transition from academic labs to the larger world, we are faced with the question about how best to shape the emerging technology and the organizations surrounding it. In this talk I will present Open Quantum Design (OQD), a nonprofit foundation with the goal of developing the world's first open-source full-stack quantum computer based on trapped ions. By releasing both the hardware and software stack under permissive open-source licences, OQD provides a collaborative sandbox accessible to academics, startups, government, policy makers, researchers, students and teachers — allowing the larger community to guide the direction of innovation. I will argue that, in addition to ensuring that emerging quantum computers remain democratic, transparent and accessible, an open-source model could also provide a more robust and high-quality technology that is less dependent on conventional commercial incentives.
Bio:
https://perimeterinstitute.ca/people/roger-melko
Event Location:
This seminar will only be available on zoom
Event Time:
Tuesday, May 27, 2025 | 1:00 pm - 2:00 pm
Event Location:
GEOG 100
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2025-05-27T13:00:00
2025-05-27T14:00:00
From malaria to ChatGPT: the birth and strange life of the random walk
Event Information:
The UBC Department of Mathematics is pleased to announce the Niven & Hugh Morris Lecture, taking place tomorrow (May 27, 2025), in GEOG 100 at UBC.
Abstract:
This engaging public talk will explore the fascinating history and surprising applications of random walks - from mosquito control in the early 20th century to their role in modern artificial intelligence. Dr. Ellenberg is an acclaimed mathematician, author, and speaker known for making complex ideas accessible and inspiring.
The Niven Lecture is an annual event that celebrates graduating mathematics students and welcomes their families and the broader community. It honours UBC alumnus Ivan Niven, a renowned number theorist and beloved expositor whose legacy continues to impact generations of learners.
Bio:
Learn More:
About Dr. Ellenberg: https://people.math.wisc.edu/~ellenberg/ and
Event Location:
GEOG 100
Event Time:
Tuesday, May 27, 2025 | 8:00 am - 10:00 am
Event Location:
BC Cancer Research Agency (675 W 10th Ave, Vancouver, BC V5Z 0B4), Boardroom first floor
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2025-05-27T08:00:00
2025-05-27T10:00:00
Advancing Quantitative Dosimetry SPECT with Open-Source Image Reconstruction, Uncertainty Estimation, and Image Generation Optimization
Event Information:
Abstract:
Over the past decade, radiopharmaceutical therapies have demonstrated considerable potential in cancer treatment. Notably, the success of the NETTER-1 and VISION clinical trials led to FDA approval of Lu-177, a beta-emitting isotope, for treating neuroendocrine tumors in 2018 and prostate cancer in 2022. Coinciding with these advancements, there has been growing interest in exploring treatment outcomes using alternative isotopes like the alpha-emitter Ac-225, which may offer enhanced therapeutic benefits. Many therapeutic isotopes also emit photons that, while not directly contributing to therapy, can be detected using SPECT imaging. This enables concurrent delivery and evaluation of patient absorbed dose: a practice that is well-established in the field of external beam radiotherapy. Although current radiopharmaceutical treatment protocols use a standard "one-size-fits-all" approach whereby all patients receive the same injected activity, it is conjectured that image-based dosimetry can be used to tailor dosimetry on an individual basis and consequently improve treatment outcome. One of the major challenges of dosimetry is minimizing and accounting for the presence of bias and uncertainty in acquired SPECT images.
This thesis contains a collection of studies aimed at improving SPECT image quality and interpretability via improvements and modifications to existing image reconstruction protocols. Chapter 2 of the work describes the development of the open-source medical imaging software PyTomography, which enabled the subsequent innovations of this work. Chapter 3 derives a collimator detector response model for SPECT reconstruction of high energy photons, such as those emitted by the daughters of Ac-225. Chapter 4 outlines a modification to existing reconstruction algorithms to permit uncertainty estimation in medical images and subsequently in image-based dosimetry. Chapter 5 explores the optimal image acquisition and reconstruction parameters for Ac-225 imaging, and Chapter 6 explores Monte Carlo based reconstruction techniques to further improve image quality.
Event Location:
BC Cancer Research Agency (675 W 10th Ave, Vancouver, BC V5Z 0B4), Boardroom first floor
Event Time:
Monday, May 26, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-05-26T11:00:00
2025-05-26T12:00:00
Family trees for fractional quantum Hall states
Event Information:
Abstract:
The fractional quantum Hall (FQH) effect arises in two-dimensional electron systems in strong magnetic fields and leads to exotic phases of matter with emergent quasiparticles known as anyons. These anyons carry fractional electric charge and exhibit braiding properties that go beyond those of bosons and fermions, allowing them to form building blocks for robust quantum codes. However, key features like their braiding properties are notoriously difficult to observe directly in experiments. One approach to gaining insight into a given FQH state — the "parent" — is to study its relationship to nearby "child" states that emerge when the magnetic field is slightly tuned. In this talk, we will present a new and more general framework for constructing FQH families, which can be applied even when previous methods cannot.
Bio:
Carolyn Zhang received her undergraduate degree from Yale University in 2017 and went on to earn her Ph.D. at the University of Chicago under the supervision of Michael Levin, supported by the NSF Graduate Research Fellowship and the Bloomenthal Fellowship. Since the fall of 2023, she has been a Junior Fellow at the Harvard Society of Fellows. Carolyn loves all activities related to mountains, including running, climbing, and hiking.
Learn More:
Watch Carolyn's videos:
Symmetries: Symmetries 2024: Carolyn Zhang (Harvard)
Anyon Condensation and its applications: https://www.youtube.com/watch?v=r8tGIniUxrg
Anomalies of (1 + 1)D categorical symmetries: https://www.youtube.com/watch?v=hSzBMYEY_q8
Event Location:
HENN 318
Event Time:
Sunday, May 25, 2025 | 1:00 pm - 3:30 pm
Event Location:
HENN 318
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2025-05-25T13:00:00
2025-05-25T15:30:00
Zero-energy Modes in Quantum Field Theories
Event Information:
Abstract:
We discuss three instances where zero-energy or soft modes appear in quantum field theory.
First, we examine massless fermions in a 2+ 1 dimensional system with a spatial boundary, specifically graphene in half-space. Two boundary conditions and their interplay with the discrete and continuous symmetries of the system are analyzed. For doubled fermions, we identify a special case that respects CP T symmetry but breaks Lorentz and conformal symmetry, featuring fermion zero mode edge states. These edge states lead to unconventional representations of scale, phase, and translation symmetries, and enforcing symmetry constraints results in edge ferromagnetism.
Second, we investigate the infrared structure of a massless scalar theory coupled to fermions. We demonstrate the existence of a field theory containing massless scalar particles that mirrors the infrared structure of quantum electrodynamics and perturbative quantum gravity but lacks gauge invariance, internal symmetries, or apparent asymptotic symmetry. Unlike soft photons and gravitons, soft scalars do not decouple from dressed states and are generally produced during interactions of hard dressed particles, though their entanglement is minimal.
Lastly, we develop a novel method to calculate changes in an operator’s expectation value at asymptotic times, relevant to gravitational wave observations, by exploiting its soft limit. We derive a formula for asymptotic in-in observables from the soft limit of five-point amputated response functions. Using this, we re-derive the KMOC formulas for linear impulse and radiated momentum during scattering and provide an unambiguous calculation of radiated angular momentum at leading order. We introduce a causal method of computing classical observables using the Schwinger-Keldysh formalism.
Event Location:
HENN 318
Event Time:
Thursday, May 22, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-05-22T11:00:00
2025-05-22T12:00:00
Collective quantum information
Event Information:
Abstract:
Quantum mechanics describes the behaviour of our world at microscopic scales. It features many mysterious and counter-intuitive phenomena which rarely impinge on our everyday lives—yet, the ability to control these effects at scale would yield new information technologies that have enormous potential for scientific and societal impact. While progress in building such quantum devices over the last several years has been extremely rapid, there is much theoretical work required to understand how best to design, test, and use these platforms, for which insights from multiple scientific disciplines will be required. In this talk, I will describe how concepts from condensed matter and many-body physics can bring about progress in quantum information science, in particular as we scale up towards the ‘many-qubit’ regime. Through understanding the emergent collective behaviour exhibited by many-body quantum systems, I will show how new protocols for quantum information processing can be developed, and how our understanding of the power of quantum computers can be advanced.
Bio:
Max McGinley is a Junior Research Fellow at Trinity College, Cambridge, working at the interface of quantum information theory and many-body physics. He received his PhD under the supervision of Prof. Nigel Cooper in 2020, before holding a postdoctoral position at the Rudolf Peierls Centre for Theoretical Physics, at Oxford University.
Learn More:
About Max: https://sites.google.com/view/max-mcginley
Event Location:
HENN 318
Event Time:
Tuesday, May 20, 2025 | 1:30 pm - 2:30 pm
Event Location:
HENN 318
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2025-05-20T13:30:00
2025-05-20T14:30:00
The emergence of Einstein gravity from topological supergravity in 3 + 1D
Event Information:
Abstract:
The topological aspects of Einstein gravity suggest that topological invariance could be a more profound principle in understanding quantum gravity. In this report, I will begin by considering a topological super-gravity action (N=1) that initially describes a universe without Riemann curvature, which seems trivial. However, after introducing a small deformation parameter λ, which can be regarded as an AdS generalization of supersymmetry (SUSY), we find that the deformed topological quantum field theory (TQFT) becomes unstable at low energy, resulting in the emergence of a classical metric, whose dynamics are controlled by the Einstein equation. Moreover, such type of TQFT can be generalized to include arbitrary N supercharge, enhancing the reliability of our saddle point calculations.
Bio:
Tianyao is a postdoctoral fellow at the Chinese University of Hong Kong Department of Physics.
Learn More:
Read Tianyao's paper, "The emergence of Einstein gravity from topological supergravity in 3 + 1D": 2312.17196
Event Location:
HENN 318
Event Time:
Friday, May 16, 2025 | 12:00 pm - 1:00 pm
Event Location:
HENN 318
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2025-05-16T12:00:00
2025-05-16T13:00:00
Collective quantum information
Event Information:
Abstract:
Quantum mechanics describes the behaviour of our world at microscopic scales. It features many mysterious and counter-intuitive phenomena which rarely impinge on our everyday lives—yet, the ability to control these effects at scale would yield new information technologies that have enormous potential for scientific and societal impact. While progress in building such quantum devices over the last several years has been extremely rapid, there is much theoretical work required to understand how best to design, test, and use these platforms, for which insights from multiple scientific disciplines will be required. In this talk, I will describe how concepts from condensed matter and many-body physics can bring about progress in quantum information science, in particular as we scale up towards the ‘many-qubit’ regime. Through understanding the emergent collective behaviour exhibited by many-body quantum systems, I will show how new protocols for quantum information processing can be developed, and how our understanding of the power of quantum computers can be advanced.
Bio:
Max McGinley is a Junior Research Fellow at Trinity College, Cambridge, working at the interface of quantum information theory and many-body physics. He received his PhD under the supervision of Prof. Nigel Cooper in 2020, before holding a postdoctoral position at the Rudolf Peierls Centre for Theoretical Physics, at Oxford University.
Learn More:
About Max: Max McGinley
Event Location:
HENN 318
Event Time:
Thursday, May 15, 2025 | 6:00 pm - 7:30 pm
Event Location:
Vancouver Public Library - Central Branch (Montalbano Family Theatre - level 8)
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2025-05-15T18:00:00
2025-05-15T19:30:00
How the Universe Works: Qunatum Mechanics - the Music of the Universe
Event Information:
Curious about how the universe actually works? Join the experts from UBC’s Department of Physics and Astronomy to find out fun facts about everything from the Milky Way to radio waves in this new, accessible science series: How the Universe Works!. All are welcome!
Abstract:
Quantum mechanics is the sometimes bizarre set of physics rules that gives our best understanding of how nature works at a fundamental level.
In this talk, Dr. Van Raamsdonk will introduce some of the key ideas of quantum mechanics -- including quantum superpositions, wavefunctions, and indeterminacy -- by describing how these are related to much more familiar ideas from the science of music and musical instruments.
Bio:
Mark Van Raamsdonk is a professor of theoretical physics at the University of British Columbia. His research areas include quantum mechanics, general relativity, string theory, and cosmology. He is also an amateur musician, specializing in jazz saxophone.
Learn More:
About Mark: https://phas.ubc.ca/~mav/vanraamsdonk.html
About quantum mechanics: https://en.wikipedia.org/wiki/Quantum_mechanics
About science and music: https://www.kennedy-center.org/education/resources-for-educators/classroom-resources/media-and-interactives/media/music/connections/connections/science--music/
Event Location:
Vancouver Public Library - Central Branch (Montalbano Family Theatre - level 8)
Event Time:
Thursday, May 15, 2025 | 11:00 am - 12:00 pm
Event Location:
HENN 318
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2025-05-15T11:00:00
2025-05-15T12:00:00
Quantum dynamics meets quantum information
Event Information:
Abstract:
Quantum computers have the potential to revolutionize both quantum simulations and classical computations. Rapid advancements in quantum hardware have not only introduced new opportunities but also posed significant theoretical challenges in understanding quantum dynamics. These developments highlight the need for benchmarking models—interacting many-body systems that can be solved exactly or numerically to assess the capabilities of quantum processors. In this talk, I will discuss powerful theoretical tools to address these challenges, focusing on the Sachdev–Ye–Kitaev (SYK) model and the emerging framework of entanglement in time, an information-theoretic approach designed to probe dynamical properties of quantum systems.
Bio:
Alexey Milekhin received his Ph.D. from Princeton University in 2020 under the supervision of Prof. Juan Maldacena. He is working at the intersection of quantum information theory, statistical physics and quantum gravity with the goal of understanding the general properties of out-of-equilibrium systems and quantum chaos.
He currently holds a postdoctoral scholarship at the Institute for Quantum Information and Matter at Caltech: Alexey Milekhin | The Division of Physics, Mathematics and Astronomy
Event Location:
HENN 318
Event Time:
Monday, May 12, 2025 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
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2025-05-12T16:00:00
2025-05-12T17:00:00
Physics of fast radio bursts and their use as cosmological probes
Event Information:
Abstract:
The detection of a Fast Radio Burst (FRB) in 2007 opened a new frontier in astronomy, a field that is rapidly evolving. The search for FRBs and the measurement of their physical properties have become major scientific objectives. Canada has been at the forefront of this effort, led by the highly successful CHIME telescope. It is now well established that most FRBs originate at cosmological distances and rank among the brightest known transients in the radio band. In April 2020, an FRB was detected within our galaxy, confirming that at least some FRBs are associated with neutron stars possessing extremely strong magnetic fields (magnetars). I will describe recent work on how these coherent, powerful radio outbursts are generated. Additionally, I will discuss how FRBs can serve as probes of the baryon distribution in the universe and as tools for studying the era of reionization.
Bio:
I am an astrophysics professor at UT and my research specialty is exploding stars and blackholes.
Learn More:
About Pawan: Kumar | McDonald Observatory
About his research: Astronomy at the University of Texas at Austin
Event Location:
HENN 318
Event Time:
Thursday, May 8, 2025 | 2:00 pm - 3:00 pm
Event Location:
HENN 318
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2025-05-08T14:00:00
2025-05-08T15:00:00
Searches for novel gravitational-wave sources with ground and space-based detectors
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Abstract:
Gravitational waves (GWs) probe the fundamental nature of neutron stars (NSs) and black holes (BHs). Observations of GWs by ground-based interferometric detectors, like the Laser Interferometer Gravitational-wave Observatory (LIGO), have yielded key insights into the formation channels of compact binaries and the physics of ultra-dense NS matter. The planned space-based Laser Interferometer Space Antenna (LISA) will detect entirely new GW sources inaccessible with present-day interferometers. In this thesis, I present new data analysis methods for ground and space-based detectors that enable future discoveries of novel GW sources.
Spinning, non-axisymmetric NSs can emit weak continuous gravitational waves (CWs). Most CW searches assume a specific phase model for the signal, but are less sensitive to sources that deviate from this model, such as NSs in binary systems. In this thesis, I describe an end-to-end CW search pipeline that is robust to a wider range of signal morphologies, combining semi-coherent matched filtering techniques with a hidden Markov model (HMM) frequency tracking scheme. Using Advanced LIGO data from the third observing run, I applied this pipeline to analyze candidate signals reported by a previous radiometer-style GW search. No credible CW signals were detected. By recovering simulated signals into detector data, I show that our approach can detect CW signals with amplitudes h ~ 9e-26 in the most sensitive frequency band (~200 Hz) of the detectors. I also apply this pipeline in a search for CWs from the Vela pulsar following a spin-up glitch.
In the second part of this thesis, I characterized the ability of LISA to detect hierarchical triple systems, consisting of a stellar-mass BH binary (BHB) orbiting a supermassive black hole (SMBH). The stellar-mass BHB component may undergo high-amplitude eccentricity oscillations due to gravitational torques exerted by the SMBH, emitting repeated GW bursts detectable by LISA. Focusing on potential BHB-SMBH triples in the Galactic centre, I used simulated LISA data to demonstrate that an unmodelled wavelet decomposition of the data recovers the time-frequency properties of each burst, and further show how this approach can be used to study the eccentricity evolution of the perturbed BHB and the dynamics of BHB-SMBH triples.
Event Location:
HENN 318
Event Time:
Tuesday, April 29, 2025 | 1:00 pm - 2:00 pm
Event Location:
HENN 318
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2025-04-29T13:00:00
2025-04-29T14:00:00
High-parallel field spectrometer extends capability of TRIUMF beta-detected nuclear magnetic resonance
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Abstract:
This thesis reports the design and implementation of a new high-parallel field spectrometer, which extends the capability of TRIUMF beta-detected nuclear magnetic resonance (beta-NMR) facility with fields up to 200 mT parallel to the sample surface.
The magnetic field range and spectrometer configuration are designed to allow nm-scale depth-resolved studies of superconducting RF (SRF) materials up to the superconducting critical field of Nb, the main material for SRF cavities. SRF cavities are the main technology behind high-energy and high-power linear accelerators (linacs) worldwide, allowing charged particle acceleration using radiofrequency (RF) accelerating gradient up to several tens of MV/m. The accelerating electric fields along the cavity axis are accompanied by the RF magnetic fields parallel to the cavity wall, which induce dissipation due to the penetrating magnetic fields contained within 100 nm layer of the cavity surface in the flux-free superconducting Meissner state.
The ability of the SRF materials to screen and contain magnetic fields within the penetration depth, as well as the maximum field limit before strongly dissipative magnetic fluxes enter the bulk of the material (and induce RF quenches of the SRF cavity), have been found to be very sensitive to different types of surface treatments. The magnetic field-dependent surface dissipation affects the operational cost of SRF cavities, and the maximum magnetic field that can be sustained in the Meissner state ultimately limits the maximum accelerating gradient of SRF cavities.
Various surface treatment recipes using heat treatment and/or impurity diffusion have been developed which demonstrate enhanced performance of SRF cavities. Complete understanding of the underlying mechanism of this enhancement, however, requires a more controlled microscopic study of the near surface layer. Depth-resolved measurements of the magnetic field screening below the surface of SRF materials are made possible with this new spectrometer, which combines local magnetic field measurements via spin-polarized radioactive ion beam (RIB) produced at TRIUMF ISAC facility (commonly uses Li-8 positive ions), and the suitable spectrometer which allows high-parallel field combined with implantation depth-control of the probing ions via deceleration of the their momentum.
The new spectrometer requires modifications of the existing beta-detected nuclear quadrupole resonance (beta-NQR) beamline, and an additional ~1 m beamline extension. The magnetic field configuration parallel to the sample surface (and initial spin polarization of the probe) but transverse to the beam momentum deflects the beam vertically and requires compensation via electrostatic steering of the RIB to deliver beam to the target sample. The details of design, assembly, various stages of beamline installation, and operations of the various elements both along the beamline and the new spectrometer are all presented in this thesis.Also provided are the test results of the new/modified components, and the commissioning results proving the functionality of the new spectrometer using RIB.
Depth-resolved measurements on two Nb samples with different surface treatments typically applied to SRF cavities have been performed on the new spectrometer up to the maximum available fields (of 200 mT). The results demonstrate the sensitivity of the beta-NMR technique in characterizing the magnetic field screening, and provide a working method for future SRF study. These results also provide comparison of the different screening responses of various Nb samples to the applied magnetic fields due to the modified surface layers. The change in the magnetic penetration depth with increased fields are then compared to various theoretical predictions on the role of the modified surface. Outlook on future experiments on different SRF materials (such as layered superconductors), as well as potential applications of the new spectrometer for other materials are proposed.
Event Location:
HENN 318