Events List for the Academic Year

Event Time: Thursday, February 29, 2024 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2024-02-29T11:00:00 2024-02-29T12:00:00 Observation of Pines' Demon in Sr2RuO4 Event Information: Abstract:Electrons confined in a material exhibit rich quantum behavior with no counterpart in free space. In particular, electron-electron interactions give rise to quantized collective particles which we can use to fundamentally understand the properties of materials. For metals, the primary collective mode of electrons is the plasmon - a quantized excitation where all the electrons move together in synchrony. In 1956, David Pines predicted another particle, known as the "demon", inside multiband metals where electrons of different "flavors" move out-of-phase with each other. For over 66 years, the demon remained undetected because demons are both gapless (i.e. massless) and do not couple to light. Nevertheless, demons are predicted to be responsible for diverse phenomena ranging from phase transitions in mixed-valence materials, "soundarons" in Weyl semimetals, and superconductivity in, for example, metal hydrides. In this talk, I will present evidence for the demon in Sr2RuO4 using the newly developed technique of Momentum-resolved Electron Energy-Loss Spectroscopy (M-EELS). Our study confirms the existence of Pines' demon and indicates that demons may be a pervasive feature of multiband metals. Finally, I will discuss emerging experimental efforts for discovering new collective particles in quantum materials that have escaped experimental identification. Bio:Ali Husain received his B.S. in Physics from the University of California, Berkeley in 2014. In 2020, he completed his Ph.D at the University of Illinois at Urbana-Champaign in condensed matter physics focusing on the problem of charge dynamics in so-called "strange" metals. From 2020-2022, Ali was the SBQMI Postdoctoral Prize Fellow at the University of British Columbia working with George Sawatzky and Steven Dierker to develop new methods for studying quantum materials using electron microscopy and spectroscopy. Since 2022, Ali has been an AMO research scientist at Quantinuum building next-generation trapped-ion quantum computers. Event Location: HENN 318
Event Time: Thursday, February 29, 2024 | 9:45 am - 10:45 am
Event Location:
BRIM 311
Add to Calendar 2024-02-29T09:45:00 2024-02-29T10:45:00 Quantum sensing in the solid-state: from one spin to many spins Event Information: Abstract: Sensors that leverage quantum phenomena to measure physical quantities harbor many attractive features beyond classical sensors. Solid-state quantum sensors, with the nitrogen-vacancy (NV) center in diamond a forefront technology, are particularly attractive for their compatibility with biological and condensed matter systems, offering ultra-high spatial resolution and sensitivity over a wide temperature range, while being quantitative and non-invasive. Here I first present our group’s work on NV-center-based scanned probe imaging of electron flow patterns in graphene, revealing the presence of hydrodynamic electron flow. A frontier of quantum sensing is the utilization of entangled quantum sensors for metrological advantage, a goal not yet realized in the solid-state. I also discuss our group’s progress towards realizing novel many-body states of entangled spins, both diamond-based qubits and novel chemically-assembled molecular spin systems. Speaker Bio: Ania Bleszynski Jayich is a professor of physics at the University of California Santa Barbara, where she holds the Bruker Endowed Chair for Science and Engineering, the Elings Endowed Chair for Quantum Science, and is co-director of the Quantum Foundry, an NSF Q-AMASE-I center. Her research interests include quantum assisted sensing and imaging on the nanoscale, spin-coupled optomechanics, and hybrid quantum systems for sensing and quantum information. Before coming to UCSB, Ania was a postdoctoral researcher at Yale University, and received her PhD in physics from Harvard in 2006 and a B.S. in physics and mathematical and computational science from Stanford in 2000. Event Location: BRIM 311
Event Time: Tuesday, February 27, 2024 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2024-02-27T11:00:00 2024-02-27T12:00:00 New frontiers in error correction and many-body physics: non-equilibrium quantum matter and non-Euclidean geometries Event Information: Abstract:  Error correction is a key ingredient towards realizing scalable quantum computation and is also of fundamental interest due to its close connection to exotic quantum phases of matter. In my talk, I will discuss some recent results at the interface of quantum error correction and quantum many-body physics. In the main part of the talk, I will discuss the problem of realizing error correction in a fully local way, without the need for non-local communication between a classical processor and the quantum device. This fits into the broader problem of classifying quantum phases of matter in dissipative open systems. I will formulate conditions for the stability of phases in open systems, putting it on a footing similar to the analysis of quantum phases of matter at zero temperature. In the last part of the talk, I will briefly discuss recent breakthroughs in the field of quantum low-density parity check (LDPC) codes, which live on highly expanding non-Euclidean graph geometries, and describe how they can be understood in the language of gauge theories, familiar from high energy and condensed matter physics. [1] Defining stable phases of open quantum systems, TR, Sarang Gopalakrishnan, Curt von Keyserlingk, arXiv 2308.15495 [2] The physics of (good) LDPC codes I: Gauging and dualities, TR, Vedika Khemani, arXiv 2310.16032  Bio: Tibor Rakovszky is a Bloch Postdoctoral Fellow in Quantum Science and Engineering at Stanford University. Previously, he completed his PhD at the Technical University of Munich in 2020. His PhD work focused on dynamics in interacting quantum systems, combining ideas from quantum information theory and many-body physics to understand the scrambling of quantum information and its relationship to thermalization and transport in closed quantum systems. He subsequently extended these studies to include the effects of local measurements on quantum dynamics. His more recent interests are at the intersection of quantum error correction and many-body physics. In particular, he is interested in the classification of quantum phases of matter in novel regimes and the use of such phases for storing and manipulating quantum information.  Event Location: HENN 318
Event Time: Friday, February 23, 2024 | 9:30 am - 11:30 am
Event Location:
Henn 318
Add to Calendar 2024-02-23T09:30:00 2024-02-23T11:30:00 Atom-Atom, Atom-molecule and molecule-molecule collisions at ultra-cold and room temperature Event Information: Abstract:  This thesis describes experiments with magnetically and optically trapped  ultra-cold gases of 6Li and 85,87Rb atoms. We describe three distinct areas of investigation, with a common theme of probing collisions: the production of deeply bound 6Li2 dimers and a study of their reactive collisions, the use of ultra-cold atoms as a pressure sensor by measuring the loss rate due to collisions with background gases at room temperature, and progress towards investigating heteronuclear collisional resonances between ultra-cold 6Li and 85,87Rb. We report on the production of deeply bound triplet a(13Σ+u ) 6Li2 molecules in a single quantum state by stimulated Raman adiabatic passage. The ensemble lifetimes for these molecules were found to be limited by dimer- dimer collisions whose rate depends on the ro-vibrational state of the collision partners. The loss rate observed follows a universal prediction for the |v = 0, 5, 8; N = 0, 2⟩ states, and remarkably, a sub-universal rate for the |v = 9; N = 0⟩ state. We find that molecules in the ground state of the triplet potential are also collisionally unstable, consistent with theoretical predictions that molecules in any of the triplet levels are chemically unstable and decay due to a barrier-less trimer formation process.  We also report on a comparative measurement of the cross section for trap loss inducing collisions of 6Li and 87Rb atoms when exposed to various common background gases found in ultra-high vacuum (UHV) environments, including H2, He, Ne, N2, Ar, Kr and Xe. Ultra-cold 6Li and 85,87Rb atoms are used as a sensitive probe of the background gas pressure, with the quantity ⟨σlossv⟩ essential for converting the observed loss rate due to background gas collisions into a pressure measurement.  Finally, we discuss the production of ultra-cold mixtures of 6Li and 85,87Rb atoms, and the progress towards investigating heteronuclear Feshbach resonances. The Feshbach resonances allow us to tune the interaction strength, which is an essential tool for investigating few and many-body physics in these systems. We discuss the particular example of the Efimov effect, which would be a natural topic of study following our investigating of the Feshbach resonance spectrum.  Event Location: Henn 318
Event Time: Thursday, February 22, 2024 | 1:00 pm - 2:00 pm
Event Location:
BRIM 311
Add to Calendar 2024-02-22T13:00:00 2024-02-22T14:00:00 Electrons in twisted layers: design, surprise, and a new set of eyes Event Information: Abstract: When two atomically-thin layers of a material are stacked one atop each other, with a relative twist angle between them, properties can emerge that bear little resemblance to the behavior of the individual layers. Though much can be predicted and designed about such structures, I will share two vignettes about how my students aimed for a particular behavior but found something quite different. The first led to the discovery of the first experimentally-known “orbital magnet”, a ferromagnet in which the tiny microscopic magnets that align with each other are not electron spins but tiny circulating current loops. The second surprise was observation of resistance that skyrocketed with the application of a magnetic field, along with other striking electronic properties — this one took years to figure out, but we’ve recently explained it. Each of these two surprises turned out to be caused by a structural feature of the layered stack which had not previously been considered important. Finally, I’ll describe a refined approach to stacking and a newly-developed technique for mapping the structure of twisted layers, which together might help us get more repeatable control of structure and thus electronic properties in such twisted systems. Event Location: BRIM 311
Event Time: Thursday, February 22, 2024 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2024-02-22T11:00:00 2024-02-22T12:00:00 Sculpting quantum many-body states and quantum error correcting codes with measurements Event Information: Abstract: Quantum mechanics exhibits a stark dichotomy between unitary time-evolution and measurement. These aspects are further contrasted by the fact that traditional many-body quantum theory is developed solely based on unitary aspects. In this talk, I will explore two fruitful synergies that emerge from the interplay between many-body quantum physics and the non-equilibrium quantum dynamics that arises from measurements. First, I will show how measurements can be used to circumvent fundamental constraints imposed by unitary dynamics and efficiently prepare a large class of topological phases of matter. In addition to discovering a new hierarchy of many-body quantum states unseen in the unitary setup and a surprising connection to the unsolvability of the quintic polynomial, our studies also yield practical protocols for quantum processors that led to the first unambiguous observation of non-Abelian anyons. Second, I will show how insights from topological phases of matter can in turn contribute to a physical understanding of the newly introduced "Floquet" quantum error correcting codes, featuring a schedule of anticommuting measurements. I will demonstrate that periodicity in time is in fact not required, unlocking a more general construction of "dynamic codes" that are capable of not just error correction, but also fault-tolerant quantum computation. Bio: Nat Tantivasadakarn obtained his undergraduate degree from UC Berkeley, his Master's from the Perimeter Institute for Theoretical Physics and his Ph.D. from Harvard University. He is currently a Burke postdoctoral fellow at Caltech. His research interests explore the interplay between topological phases of matter, quantum error correction and computation, non-equilibrium quantum dynamics and generalized symmetries.   Event Location: HENN 318
Event Time: Thursday, February 15, 2024 | 11:00 am - 12:00 pm
Event Location:
HENN 318
Add to Calendar 2024-02-15T11:00:00 2024-02-15T12:00:00 Long-lived superconducting quantum circuits toward fault-tolerant quantum computing Event Information: Abstract:Superconducting quantum circuits represent fully engineerable quantum systems, positioning them as a leading platform for large-scale quantum computing. Despite recent milestones like surface code demonstrations and achieving quantum supremacy, scaling up to millions of qubits for fault-tolerant operations remains a significant challenge. Our research focuses on enhancing qubit lifetimes within superconducting quantum circuits to reduce resource requirements significantly. We pursue two primary strategies: Firstly, we investigate the loss mechanisms affecting state-of-the-art superconducting qubit lifetimes. By careful optimization of the fabrication process, sample packaging, and cryogenic wiring, we demonstrate long-lived superconducting qubits, recording one of the best qubit lifetimes (> 0.5 milliseconds). By leveraging these long-lived qubits as quantum sensors, we identify a new loss mechanism attributed to mechanical shocks from the pulse tube cooler of a dilution refrigerator. This discovery suggests new error mitigation strategies by isolating superconducting qubits from mechanical environments. Secondly, we introduce mechanical oscillators based on circuit optomechanics, facilitated by a novel nanofabrication process involving silicon-etched trenches. This breakthrough enables the realization of ultra-coherent and highly scalable systems (> 10 milliseconds and > 20 modes), leading to the first demonstrations of tracking the thermalization of a mechanical squeezed state and engineering topological optomechanical lattices. These advancements not only bring insights into decoherence mechanisms but also pave the way for scalable fault-tolerant quantum computing. Event Location: HENN 318
Event Time: Thursday, February 15, 2024 | 9:45 am - 10:45 am
Event Location:
BRIM 311
Add to Calendar 2024-02-15T09:45:00 2024-02-15T10:45:00 Frustrated Quantum Devices: understanding how correlations, complex order and boundary states manifest in novel material functionalities Event Information: Abstract: Materials at the boundary of critical phase transitions are of significant fundamental interest, not least due because of their connection to unconventional superconductivity and quantum magnetism. One characteristic of such systems is the presence of coupled order parameters that underlie these phase transitions. Here, we explore how this coupling manifests in the response of these materials when driven out of equilibrium by applied currents. We demonstrate how magnetic and charge textures can be electrically manipulated, suggesting possible applications for exotic materials in spintronics technologies. Event Location: BRIM 311
Event Time: Monday, February 12, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar 2024-02-12T16:00:00 2024-02-12T17:00:00 A machine learning lens on galaxy mergers in the nearby Universe Event Information:   Abstract:  Merger events are thought to interrupt the otherwise gradual evolution of galaxies with short periods of intense change, simultaneously transforming galaxy morphologies, fueling bursts of star formation, and giving rise to high accretion rates onto central supermassive black holes. In this talk, I will demonstrate how machine vision techniques have fundamentally changed the way mergers are identified and studied and highlight new observational results that constrain the influence of mergers on the evolutionary trajectory of galaxies. While some of these results highlight the elegance of the current paradigm for hierarchical galaxy growth, others point to complications brought on by the multi-wavelength diversity of galaxies, stars, and supermassive black holes in the Universe.   Bio:  Bobby Bickley is an astronomy Ph.D. candidate at the University of Victoria (unceded Lekwungen territory, Victoria BC). He also holds a B.Sc. in mechanical engineering from the University of Connecticut. Bobby’s research interests are galaxy evolution, galaxy mergers, supermassive black hole & galaxy co-evolution, and the application of machine learning techniques to problems in astronomy. Event Location: HENN 318
Event Time: Thursday, February 8, 2024 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar 2024-02-08T14:00:00 2024-02-08T15:00:00 Megajoule Fusion Yields at the National Ignition Facility (shared with UBC) Event Information: Abstract: With 192 laser beams delivering over 2 megajoules of energy to target, the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is the world's most energetic laser system and, for the first time in a controlled laboratory setting, has demonstrated fusion ignition and target gain greater than 1. The NIF generates ignition conditions by precisely firing the lasers onto a target comprising a centimeter-tall cylinder inside of which is a millimeter-scale spherical shell filled with deuterium-tritium fuel. The fuel highly compresses, fusing the deuterium and tritium to release helium and large quantities of neutrons and energy. A series of advances over the course of decades were required to reach this stage - laser optical components, target fabrication precision, and implosion design. Building from here, the momentous demonstration of reproducible ignition paves the way for a new category of ignition science experiments as well as a broad array of materials and nuclear science studies within a novel regime of high energy density physics. Bio:  Berzak Hopkins is a design physicist at Lawrence Livermore National Laboratory, focusing on inertial confinement fusion experiments on the National Ignition Facility (NIF). She has already has made a mark at NIF as part of the team that performed the first shots to show more energy coming out of the hydrogen fuel than was deposited in it. While still short of ignition – when the energy out is greater than that needed to spark the fusion reaction – it’s a big step forward. Laura also runs a website designed to connect the public to science research. “My goals continue to be to pursue what challenges me and what I feel passionate about, both in the arena of scientific research as well as in science policy and politics”. Learn More: See Laura's bio from the Lawrence Livermore National Laboratory website Review her research here Event Location: TRIUMF Auditorium
Event Time: Thursday, February 8, 2024 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2024-02-08T10:00:00 2024-02-08T11:00:00 Ultrafast optoelectronic circuits Event Information: Abstract: Ultrafast optoelectronic circuits offer new opportunities for investigating and controlling the electrical responses of microstructured quantum materials and heterostructures at femtosecond timescales and THz frequencies. Based on metal waveguides and laser-triggered photoconductive switches, these chip-scale circuits can be interfaced to quantum materials to directly probe the ultrafast flow of electrical currents or perform near-field THz spectroscopy on length scales orders of magnitude smaller than the diffraction limit. In this talk, I will present on my group’s activities using these circuits to study the electrical transport properties of quantum materials driven out of equilibrium by femtosecond laser pulses [1]. In monolayer graphene, we observe an anomalous Hall effect induced by circularly polarized light in the absence of an applied magnetic field [2]. The dependence of the effect on a gate potential used to tune the Fermi level reveals multiple features that reflect the formation of a photon-dressed, or “Floquet-engineered”, topological band structure. The results are a critical first step towards realizing and controlling light-induced topological edge states. I will also discuss our recent results on the Weyl semimetal Td-MoTe2, where we observe rectified photocurrents that scale linearly with the applied laser field. This scaling violates the perturbative description of nonlinear optics/transport, but can be explained by the formation of a photon-dressed magnetic Weyl semimetal state. In the second part of my talk, I will present on my group’s efforts in using femtosecond voltage pulses generated on-chip to probe and manipulate gate-tunable van der Waals heterostructures embedded in plasmonic cavities. We perform near-field time-domain THz spectroscopy on these cavities to study the light-matter hybridization. We observe coherent plasmon cavity modes that can be tuned from the weak to ultrastrong coupling regimes with electrostatic gating and cavity geometry. These techniques, which we are extending to mK temperatures and strong magnetic fields, could be used to investigate and control a wide range of topological and strongly correlated phenomena in microstructured quantum materials and heterostructures that fall on the THz/meV energy scale. Event Location: BRIM 311
Event Time: Wednesday, February 7, 2024 | 3:00 pm - 4:00 pm
Event Location:
Henn 318
Add to Calendar 2024-02-07T15:00:00 2024-02-07T16:00:00 FPGA-based Data Acquisition and Instrumentation in Astrophysics Experiments Event Information: Abstract: The recent advancement of Field-Programmable-Gate-Array (FPGA) technology has made them more appealing for experimental astrophysics. These experiments typically require fast and parallel processing of huge amount of data with customizable computation in terms of signal-processing chain and bit depth. Today, FPGAs come with a variety of high-speed Analog-to-Digital data converters (ADCs), high-speed serial transceivers and configurable interfaces for standard peripherals: DDR4, PCIe, 10G Ethernet. The integration of these blocks and the programmable fabric on the same chip provides lower power consumption, higher integration (or smaller footprint) which in turn helps scalability and flexibility needed for astrophysics experiments. Here, we present an example implementation of a 2-channel Spectrometer readout on Xilinx RFSoC 4x2 platform. Event Location: Henn 318
Event Time: Wednesday, January 31, 2024 | 3:00 pm - 4:00 pm
Event Location:
Henn 318
Add to Calendar 2024-01-31T15:00:00 2024-01-31T16:00:00 Remarks on Gravitational Waves from Spinning Neutron Stars Event Information: RECORDING AVAILABLE AT: https://drive.google.com/file/d/1xMX95y1b9v0X1tmEtx-WgEU-keszFKpZ/view?usp=sharing Abstract: I have not published on this topic for over 20 years, but I feel it could be useful to critically discuss some old and new articles and ideas. My aim is to focus on the basic or almost basic physics. Event Location: Henn 318
Event Time: Tuesday, January 30, 2024 | 11:00 am - 1:00 pm
Event Location:
MSL room 226 with a hybrid option

Zoom link: https://ubc.zoom.us/j/3770243649?pwd=Y2VCdXoxM0wyRFhQVWFlQ2RhQWFRQT09&omn=68781685568
Meeting ID: 377 024 3649 Passcode: 514771
Add to Calendar 2024-01-30T11:00:00 2024-01-30T13:00:00 Studies of supercoiling-induced denaturation within DNA plasmids using single-molecule Convex Lens-induced Confinement microscopy Event Information: Abstract: DNA, RNA and proteins, which drive life, have complicated, constantly changing structures. For example, DNA inside cells is supercoiled, and the amount of supercoiling is constantly under flux. This supercoiling can drive structural transitions, such as AT-rich regions in under-twisted DNA denaturing under physiological conditions. Such denatured regions may have important functions. For example, denatured DNA can act as targets for single-stranded binding proteins which help regulate gene expression. Thus, it is important to develop tools and studies to better understand these structures.In this thesis, we use single-molecule Convex Lens-induced Confinement(CLiC) microscopy in conjunction with chemical footprinting to study the biophysics of these denaturation sites, with a particular focus on the Far Upstream Element (FUSE) region of the c-myc oncogene. First, we studied the out-of-equilibrium dynamics of such denaturation after a temperature perturbation. We found that the rate of transition of the denaturation site was dependent on the direction of the perturbation, with plasmids that were heated first exhibiting a slower relaxation than plasmids that were chilled. We hypothesized that unidentified secondary structures caused this hysteresis. Second, we developed a fluorescent probe based on a molecular beacon to improve the CLiC microscopy oligo-DNA binding assay used for detecting single-stranded DNA. The final design was a stemless molecular beacon with a fluorophore on one end and a quencher on the other. This design allowed for a 10- to 100-fold increase in probe concentration used in this assay and enabled simultaneous measurements of the states of two denaturation sites within one plasmid. Finally, we studied competition between two denaturation sites within the same plasmid. We found that at low superhelicities only one site could open, while higher superhelicities allowed both to open within the same plasmid. However, we predicted that adding a specific second denaturation site would suppress the opening of the first, which we did not observe. Overall, this work provides new insights into the behaviour of DNA secondary structures, both out-of-equilibrium and under competition, and develops new tools to better study the structural biology of DNA.  Event Location: MSL room 226 with a hybrid option Zoom link: https://ubc.zoom.us/j/3770243649?pwd=Y2VCdXoxM0wyRFhQVWFlQ2RhQWFRQT09&omn=68781685568 Meeting ID: 377 024 3649 Passcode: 514771
Event Time: Monday, January 29, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar 2024-01-29T16:00:00 2024-01-29T17:00:00 What do JWST Observations infer about Galaxy Formation and LCDM? Event Information:   Abstract: The biggest news story from the first year of the James Webb Space Telescope is the existence of many more high-redshift galaxies than previously expected. This has sometimes been taken to extreme levels by suggesting that our understanding of galaxy formation in the cold dark matter model is fundamentally broken. I will discuss some of these first year results and explain what they are really telling us. I will show several results from the CAnadian NIRISS Unbiased Cluster Survey, CANUCS, and discuss their impact on this area of research.  Bio: I am a Senior Research Officer (Astronomer) working in the Canadian Astronomy Data Centre group. My research interests are primarily in cosmological evolution, particularly the growth of black holes and massive galaxies. I use data from radio to X-rays to identify and understand galaxies and quasars up to the highest redshifts known. I am involved in the development of future observatories the James Webb Space Telescope and the Square Kilometre Array.   Learn More: See Chris' Herzberg website here See his personal website here Read more about the Canadian Astronomy Data Centre    Event Location: HENN 318
Event Time: Friday, January 26, 2024 | 12:00 pm - 1:00 pm
Event Location:
HENN 318
Add to Calendar 2024-01-26T12:00:00 2024-01-26T13:00:00 The Callan Rubakov Effect Event Information: Abstract:  The Callan Rubakov Effect describes the interaction between (massless) fermions and a smooth monopole in 4d gauge theory. In this scenario, the fermions can probe the UV physics inside the monopole core which leads to interesting effects such as proton decay in GUT models. However, the monopole-fermion scattering appears to lead to out-states that are not in the perturbative Hilbert space. In this talk, we will review this issue and propose a new physical mechanism that resolves this long-standing confusion.   Bio: T. Daniel Brennan is a Physics postdoc at UC San Diego. His research focuses on applying the framework of generalized global symmetries to study strongly coupled quantum field theories. Daniel was previously a postdoctoral fellow at the University of Chicago and received his PhD from Rutgers in 2019.  Event Location: HENN 318
Event Time: Thursday, January 25, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 202
Add to Calendar 2024-01-25T16:00:00 2024-01-25T17:00:00 Discussion: The TA Experience in our Department Event Information:   Abstract: In our first colloquium next week, our course coordinator Megan Bingham will host a discussion about the TA experience in our department. At the end of  2023, we learned that filling TA positions, particularly Head TA positions, has been challenging. There are, of course, many different reasons why this is the case, including the need for TAs to focus on research and finishing their theses. However, there could be other issues that have to do with what being a TA actually entails and so an open discussion could be helpful. We therefore want to encourage our grad students to participate in the discussion and tell us about their good and not so good experiences. An important question in this context is how the department and instructors can support TAs better. (Think of it as a start/stop/keep survey). We invite instructors to listen and contribute productive ideas, but the bulk of the contributions should come from TAs. The overall goal of the discussion will be to collect ideas that could lead to more enjoyable TA experiences; in turn, benefiting the students. To help us organize the discussion around common themes. we invite our grad students to provide input via an anonymous one-question survey on Qualtrics or an email to Megan (megan.bingham@ubc.ca) that will be treated confidentially. You will find the link here.     Event Location: HENN 202
Event Time: Thursday, January 25, 2024 | 10:00 am - 11:00 am
Event Location:
AMPL 311
Add to Calendar 2024-01-25T10:00:00 2024-01-25T11:00:00 Many-Body Exciton Polariton Quantum Dynamics in Optical Microcavities based on two-dimensional Metal-Halide Semiconductors Event Information: Abstract: Two-dimensional analogs of metal-halide perovskites represent a promising platform for exciton-polariton-based technologies. They sustain strongly bound excitons that are stable at room temperature, readily enabling strong light-matter coupling at ambient conditions. In the strong coupling limit, uncoupled excitons have been mainly regarded as a reservoir for the polariton population. In this work, we posit that there is a bidirectional interplay between the uncoupled exciton dynamics and the polariton quantum dynamics. We fabricated a Fabry-Pérot microcavity, enclosing a two-dimensional hybrid organic-inorganic lead-iodide semiconductor, and resolved the multi-particle correlations of exciton-polaritons — that is their population and coherence dynamics — employing excitation correlation photoluminescence and two-dimensional coherent excitation spectroscopies. We find (i) an increased exciton bimolecular scattering rate of the exciton reservoir in the microcavity relative to the bare semiconductor; (ii) ultrafast population transfer from the uncoupled exciton states and the middle polariton to the lower polariton; and (iii) two-quantum correlations between polaritons and uncoupled excitons. Our work quantifies many-body correlations between bare excitons and exciton-polaritons, which are fundamental in mechanisms of the formation of polariton condensates. Speaker Bio: Carlos Silva-Acuña is the Director of the Courtois Institute and a Professor at the Department of Physics at Université de Montréal. Event Location: AMPL 311
Event Time: Wednesday, January 24, 2024 | 3:00 pm - 4:00 pm
Event Location:
Henn 318
Add to Calendar 2024-01-24T15:00:00 2024-01-24T16:00:00 Searching for continuous gravitational-wave emission associated with stochastic radiometer candidates Event Information: Abstract: Continuous gravitational waves (CWs) from spinning, non-axisymmetric neutron stars can reveal novel insights into the physics of neutron star interiors, but have so far gone undetected. Searches for CWs in gravitational-wave interferometer data generally assume a phase-coherent signal over the observation period. Un-modelled methods, such as the All-Sky All-Frequency (ASAF) radiometer search for stochastic gravitational waves, may reveal CW signals which randomly wander in frequency, e.g. due to spin-up glitches or accretion torques. I will present results from a CW search of Advanced LIGO data from the third observing run (O3), which targets these ASAF sub-threshold candidates. Our search algorithm combines template-based matched filtering techniques with the Hidden Markov model (HMM) formalism, allowing the signal to undergo a random walk in frequency. We find no convincing evidence of CWs associated with the ASAF candidates in O3 data. We estimate our sensitivity by running the search on simulated signals. Event Location: Henn 318
Event Time: Monday, January 22, 2024 | 4:00 pm - 5:00 pm
Event Location:
HENN 318
Add to Calendar 2024-01-22T16:00:00 2024-01-22T17:00:00 How do environmental processes quench cluster galaxies? Event Information: Abstract: The Virgo Environment Traced in CO Survey (VERTICO) is an Atacama Large Millimeter/submillimeter Array Large Program that has mapped the distribution and kinematics of star-forming molecular gas across 51 Virgo Cluster satellite galaxies on sub-kpc scales.  In this talk, I will showcase VERTICO results revealing how environmental mechanisms actively remove molecular gas, alter its distribution, and change the composition of the interstellar medium in cluster galaxies. I will also show that ram pressure stripping systematically increases molecular gas densities and triggers star formation activity on the leading half of the galaxy during the early stages of cluster infall, while lengthening gas depletion times and quenching galaxies in the latter stages.   Bio: How do galaxies evolve? is the question at the heart of my research. In search of answers, I examine the relationships between the gas in galaxies - as the fuel for forming new stars - and their stellar, star formation, and chemical properties. My specialism lies in the analysis of large multi-wavelength datasets in order to understand galaxy populations as a whole. I lead VERTICO, the Virgo Environment Traced in CO survey, an ongoing ALMA Large Program that is investigating the effect of extreme environments on galaxies by mapping the star-forming molecular gas in 51 galaxies in our nearest galaxy cluster, Virgo. VERTICO is the first ever Canadian-led ALMA Large Program and our team is made up of world-class researchers from all over the world who are working to reveal the physical mechanisms that drive galaxy evolution in dense environments in brilliant detail.   Learn More: View Toby's website here: https://drtobybrown.com See his Youtube video on Extreme Cosmos here; see his Vimeo video from FameLab Australia on how Dark Matter shapes the universe here. Learn about VERTICO the Virgo Environment Traced in CO survey.    Event Location: HENN 318