Events List for the Academic Year
Event Time:
Wednesday, October 21, 2020 | 9:00 am - 11:00 am
Event Location:
via Zoom
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2020-10-21T09:00:00
2020-10-21T11:00:00
Final PhD Oral Examination (Thesis Title: “A linear Paul trap for barium tagging of neutrinoless double beta decay in nEXO”)
Event Information:
Abstract:
nEXO is the next-generation Enriched Xenon Observatory searching for neutrinoless double beta decay (0νββ) in ¹³⁶Xe. If observed, 0νββ will validate neutrino to be its own anti-particle and determine the absolute mass scale of the neutrinos. nEXO's sensitivity is limited by the background level. Barium tagging is the ultimate background rejection method using the coincidence detection of ¹³⁶Ba as the daughter nucleus.
A linear Paul trap (LPT) is needed for the barium tagging concept in nEXO or a future gaseous experiment. The theory of an ideal LPT were studied from the first principles to obtain semi-analytical solutions of the trapped ions and to validate a simulation method. Then simulations were done to optimize the design of a realistic LPT. A setup of the designed LPT was manufactured. Meanwhile, prototypes of key components of the LPT were built for the experimental developments. A prototype of the LPT's quadrupole mass filter (QMF) achieved mass resolving power m/Δm≈140, exceeding the requirement. A 3D printed prototype of the ion cooler demonstrated successful ion cooling, trapping and ejection. Based on the progress with the prototypes, improvements were made to the LPT design and have been included in the final setup. The final LPT will be installed between an RF funnel and a multi-reflection time-of-flight mass spectrometer for detailed study of barium ion extraction and identification from gaseous or liquid xenon.
Event Location:
via Zoom
Event Time:
Monday, October 19, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-10-19T15:00:00
2020-10-19T16:00:00
Estimating star-formation histories from galaxy spectra and the path to life-finding NIR detectors
Event Information:
The evolution of galaxies can be conveniently broken down into the
evolution of their contents. We focus on the stellar content that can be observed, as the stars reflect information about the galaxy when they were formed. We approximate the stellar content and star formation histories of unresolved galaxies using stellar population modeling. We can use stellar population modeling of galaxies to test galaxy evolution and formation models. However, in the limit of low galaxy surface brightness, integrated spectra often have such low S/N that it hinders analysis with standard stellar population modeling techniques. To address this problem, we have developed a method that can recover galaxy star-formation histories (SFHs) from rest-frame optical spectra with S/N ~ 5 Å^-1, with a specific application to quasar host galaxies. We use the machine-learning technique "diffusion k-means" to tailor the stellar population basis set, composed of 4 broad age bins, and it is successful in recovering a range of galaxy SFHs. Our method has the advantage in recovering information from quasar host galaxies and could also be applied to the analysis of other low S/N galaxy spectra such as that typically obtained for high redshift objects and integral-field spectroscopic surveys. I have now begun using diffusion k-means to generate a multi-metallicity basis set to estimate the stellar mass and chemical evolution of unresolved galaxies. In addition, I have begun work to fully characterizing today's HgCdTe photodiode arrays to lay the foundation for future near infrared detector development. Low read noise and well-characterized detectors are crucial in the emerging search for biosignatures in exoplanet atmospheres.
Event Location:
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Event Time:
Thursday, October 15, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-10-15T16:00:00
2020-10-15T17:00:00
Project Lab PPE - What we learned in six months of trying to help
Event Information:
In March, the Engineering Physics Project Lab, working with several partners, kicked off a number of projects to develop personal protective equipment (PPE) for the COVID-19 pandemic. In a chaotic six months the group connected with many levels of government, health care, regulatory, and industry, first trying to figure out what problems needed to be solved (Doing the right thing) and then trying to rapidly come up with solutions that would actually work and satisfy regulatory requirements (Doing things right). The team is now wrapping up their main project, which will (hopefully) soon be approved by WorkSafe BC as a backup in the event of ongoing N95 shortages.
Dylan Gunn, the Director of the Project Lab, will recap the team's path and reflect on the question: If the pandemic had been just a little bit worse, would Canada have been able to supply itself with PPE in time to avert a disaster?
Event Location:
Connect via zoom
Event Time:
Thursday, October 15, 2020 | 2:00 pm - 3:00 pm
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Meeting ID: 657 8412 2083
Passcode: 113399
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2020-10-15T14:00:00
2020-10-15T15:00:00
CM Seminar - The magic of twisted bilayer graphene with spin-orbit coupling
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Event Time:
Thursday, October 8, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-10-08T16:00:00
2020-10-08T17:00:00
Seeking clues on why matter won over anti-matter
Event Information:
One of the most intriguing mysteries of nature is why there is more matter in the universe than anti-matter, given that the basic laws of particle physics do not appear to allow for it. One promising direction of explanation attacks the conservation of baryon number, which I will argue is one of the most vulnerable principles in fundamental physics. Forthcoming proton decay and neutron oscillations experiments may reveal much about just how the universe managed to make us and not anti-us.
Event Location:
Connect via zoom
Event Time:
Thursday, October 8, 2020 | 2:00 pm - 3:00 pm
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Meeting ID: 657 8412 2083
Passcode: 113399
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2020-10-08T14:00:00
2020-10-08T15:00:00
CM Seminar - Programming a small superconducting quantum processor with quantum instructions
Event Information:
Abstract: A quantum algorithm consists of a sequence of operations and measurements applied to a quantum processor. To date, the instructions defining this sequence have been provided by a classical computer and passed via control hardware to the quantum system. I will discuss our recent results showing the first use of quantum instructions: a fixed sequence of classically-defined gates performs an operation that uniquely depends only on the setting of an auxiliary quantum instruction state [1] (the Density Matrix Exponentiation algorithm [2]). The ability to directly use quantum instructions, without tomographically reconstructing and recompiling the quantum input into an equivalent set of classical instructions opens the door to exponential speedups in many algorithms, including principal component analysis of large quantum states [2], quantum semi-definite programming [3], and efficient measurement of entanglement spectra [4]. The algorithm is executed on two superconducting transmon qubits, with a 99.7% fidelity controlled-phase gate (measured with randomized benchmarking), and we demonstrate circuits to depth 70 with algorithm fidelities close to 90%. To achieve this performance we developed several novel strategies for tuning up quantum gates specifically in the context of structured quantum algorithms. Finally, to demonstrate the algorithm we developed a stochastic quantum operation which approximately resets a known quantum state without using classical feedback, with applications to open-loop error mitigation in logical states [5].
Refs
[1] M. Kjaergaard, M. Schwartz et al, arXiv:2001.08838 (2020)
[2] S. Lloyd et al, Nat. Phys, 10 (2014)
[3] F. Brandao et al arXiv:1710.02581 (2017)
[4] H. Pichler et al, PRX, 6, (2016)
[5] A. Greene, M. Kjaergaard et al, in preparation (2020)
Bio: Morten Kjaergaard is currently a postdoc in the Engineering Quantum Systems group with Will Oliver at MIT. His research focuses on both experimental and theoretical aspects of implementing small scale quantum algorithms and error correction, as well as extensible, practical approaches to quantum verification and validation techniques. From November 2020 he will take up position as Assistant Professor at the Center for Quantum Devices in University of Copenhagen where his group will continue research in both foundational and applied quantum information processing using superconducting qubits.
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Event Time:
Monday, October 5, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-10-05T15:00:00
2020-10-05T16:00:00
The Latest Results from the LIGO-Virgo O3 Observing Run
Event Information:
As we approach the fifth anniversary of the first detection of gravitational waves from a binary black hole merger, the LIGO and Virgo detectors have collected an impressive census of compact binary mergers in the local universe. By the end of the second observing run in August 2017 the LIGO Scientific Collaboration and Virgo Collaboration claimed a total of 10 binary black hole mergers and one binary neutron star merger. The third observing run spanned April 2019 through March 2020, during which the collaborations alerted the astronomical community of 56 merger candidates. Thus far, the exceptional events announced by the collaboration include GW190425, GW190412, GW190814, and GW190521. I will present some of what ground-based gravitational wave astronomy has taught us about compact binaries over the last five years, and what may lie ahead.
Event Location:
Connect via zoom
Event Time:
Friday, October 2, 2020 | 9:00 am - 12:30 pm
Event Location:
Virtual (link will be provided upon registration)
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2020-10-02T09:00:00
2020-10-02T12:30:00
E&I Workshop: Creating an Inclusive, Anti-Racist Environment
Event Information:
Equity & Inclusion in PHAS present “Creating an Inclusive, Anti-Racist Environment”, a workshop run by astrophysicists Dr. Kartik Sheth and Dr. Renée Hložek.
Kartik and Renée are passionate and engaging speakers, with many years of hands-on experience working on improving the representation of under-represented groups in academia. This workshop will raise awareness of the issues currently faced by the black, indigenous, and people of colour (BIPOC) community in academia, especially in physics and astronomy, and outline five steps that we as a department can follow to eliminate racism for future generations. It will be action oriented, with the goal of collaboratively developing a set of concrete initiatives that can be implemented within the department to create change sooner rather than later.
Please register below by Thursday, October 1st. There are no fees for registering, and no fees for attending the workshop.
Date: Friday, October 2nd, 9:00am – 12:30pm via Zoom
Registration fee: free.
To register: https://ubc.zoom.us/meeting/register/u5Mrd-qvrz8tEtGDqhTIwz13UojxMhIC0w5Z
Pre-reading materials:
Chapter 1-4 of How to be an antiracist – book by Ibram Kendi: Available as ebook through UBC libraryhttps://ebookcentral.proquest.com/lib/ubc/detail.action?docID=6062443
White Fragility – article by Robin DiAngelo: https://libjournal.uncg.edu/ijcp/article/viewFile/249/116
Further readings can be found on the Resources: Reading page.
Event Location:
Virtual (link will be provided upon registration)
Event Time:
Thursday, October 1, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-10-01T16:00:00
2020-10-01T17:00:00
Investigating "official" UFO videos
Event Information:
Abstract: In 2020 the US Navy officially released three videos of UFOs, or, as they call then "UAPs" – Unidentified Aerial Phenomena. The media and the UFO community got really excited. One video appears to show a cigar-shaped craft performing impossible maneuvers, one seems to be a very fast, low flying but oddly cold craft, the most interesting one seems to show an actual flying saucer flying along then rotating to hover on its edge. But what do these videos actually show? I discuss the overlooked information in the videos, how I extracted it, mistakes people made in their analyses, and the challenges of communicating all this to an audience with only an average understanding of geometry, infrared optics, and physics.
Bio: Mick West is the author of "Escaping the Rabbit Hole - How to Debunk Conspiracy Theories Using Facts, Logic, and Respect" and host of the podcast: "Tales From The Rabbit Hole". He's a retired videogame programmer who helped make the Tony Hawk's Pro Skater Franchise. Mick runs the web site Metabunk.org, where he investigates conspiracy theories, debunks pseudoscience, and investigates UFO videos.
Event Location:
Connect via zoom
Event Time:
Thursday, October 1, 2020 | 2:00 pm - 3:00 pm
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Meeting ID: 657 8412 2083
Passcode: 113399
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2020-10-01T14:00:00
2020-10-01T15:00:00
CM Seminar - The minimal physical picture needed to understand gapping, displacements, mass enhancement, and disproportionation in 3d
Event Information:
Abstract: In his seminal work, N. Mott theorized that the insulating behavior of 3d transition metal oxides emerges This perspective created a general position in the literature that mean-field approaches such as DFT are inappropriate for describing the broad science issues of 3d oxides. The indispensability of the highly correlated approach builds upon illustrations that DFT fails to explain the insulating state of paramagnets, orbital ordering, mass -enhancement, even Jahn-Teller distortions. Upon a closer examination described here one finds that these failures apply to highly-symmetric minimal unit cell models containing only the least number of possible magnetic, orbital and structural degrees of freedom. We explored the alternative option of staying within mean field DFT, but avoiding Naïve (N)-DFT approximations that do not define what DFT can do. Specifically, we allow symmetry breaking (such as local displacements; avoiding equal occupation of degenerate levels, avoid forcing zero moments on each atomic site in paramagnets) if it lowers the total DFT energy. This generalization creates (even without U) finite band gaps in AFM and PM phases of ABO3 perovskites (except PM SrVO3 and CaVO3 that are metals), disproportionation (in SmNiO3 and YNiO3), mass enhancement (in SrVO3 ,LaMnO3 SrBiO3) and explains the observed trends in Jahn-Teller distortions throughout the series. Symmetry breaking in approximate mean-field theory could capture events that in restricted symmetric structures would require a complex correlated treatment. This is consequential, as it opens the door for (non-naïve) DFT treatment of complex d electron systems including interfaces, defects and doping that do not depend on details of multiplets.
Biography: Prof. Alex Zunger of the University of Colorado, Boulder research field is Condensed Matter Theory of Real Materials, involving foundational work on Density Functional Theory, Pseudopotential theory, Quantum Nanostructures, Photovoltaic materials and Materials by Design ( website:; http://www.colorado.edu/zunger-matter-by-design/). He is widely credited with foundational work and leadership in the now classical field of “First Principles theory of solids”, a predictive approach to electronic, structural and thermodynamic properties of matter, given the atomic identities and composition. He published over 700 journal articles in this discipline, delivered many hundreds of talks in physics and materials societies, and mentored 84 postdoctoral fellows, many of who are now leading scientists around the world.
He is the recipient of the year 2018 Boer Medal for photovoltaic research, the 2013 TMS Hume- Rothery Award on Theory of alloys, the 2011 (inaugural) “Materials Theory Award” of the Materials Research Society on Inverse Design, the 2010 “Tomassoni Prize“ (Italy) and “2010 Medal of the Schola Physica Romana “ celebrating the tradition of E. Fermi, the 2001 John Bardeen award of The Material Society on “Spontaneous Ordering in semiconductor alloys”, the 2001 Rahman Award of the American Physical Society on ‘foundational development of First Principles methods’, and the 2009 Gutenberg Award (Germany) on correlated electron systems. He is a Fellow of the American Physical Society; Fellow of the Materials Research Society, Sakler Fellow of the Institute of advanced studies (Tel Aviv University). The impact of Dr. Zunger’s work is partially reflected by the high number of citations his papers have received (over 100,000, according to Google Scholar) and by his “h-number” of more than 145 (i.e., 145 of his papers were cited each at least 145 times). He is the author of the fifth-most-cited paper in the 110-year history of Physical Review (out of over 350,000 articles published in that journal) .In the course of his research; he has authored more than 700 articles in refereed journals, which includes over 150 articles in Physical Review Letters and Rapid Communications (PRB) and three citation classics. Declared by the Institute of Scientific Information (ISI) as the 39th most-cited physicist out of more than 500,000 physicists examined, based on publications in 1981–1997 in all branches of physics.
Event Location:
https://ubc.zoom.us/j/65784122083?pwd=U09vVXJMRzNLaTY3bmVXNEFJZ1k3UT09
Meeting ID: 657 8412 2083
Passcode: 113399
Event Time:
Monday, September 28, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-09-28T15:00:00
2020-09-28T16:00:00
The continuing struggle for dark skies
Event Information:
Being the Director of the Rothney Astrophysical Observatory has led me down many trails, but none more astounding, energy draining, thought provoking, aggravating and rewarding, than the struggle to keep the stars sparkling above the RAO. I will share stories of my interactions with: The City of Calgary and Transportation Alberta through the UCalgary Community and Government Relations office, The Foothills County Municipality, urban Community Development planners and Ring Road construction companies, The Ann & Sandy Cross Conservation Area, the RASC Calgary Centre, and the neighbors who live adjacent to the RAO. (I'm sure I've forgotten somebody...)
Event Location:
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Event Time:
Thursday, September 24, 2020 | 4:00 pm - 5:00 pm
Event Location:
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2020-09-24T16:00:00
2020-09-24T17:00:00
Faculty 3-minute presentations
Event Information:
List of presenters and titles. Email names (@phas.ubc.ca) have been added (in bold) to help with communcation.
Steven Plotkin (steve) "The physical origins of multicellular animals"
Ingrid Stairs (stairs) "Pulsars and FRBs"
Aaron Boley (acboley) "Planets, Debris, and Us"
Chris Hearty (hearty) "Searching for the Dark Sector with the Belle II experiment"
Joshua Folk (jfolk) "Exploring exotic states with quantum electronics"
Ludovic van Waerbeke (waerbeke) "Exploring the nature of dark matter"
Andrea Damascelli (damascelli) "Quantum Materials: from Frequency to Time Domain"
Paul Hickson (hickson) "New developments in optical/infrared instrumentation"
Joerg Rottler (jrottler) "From atomistic simulations to material behavior"
Brett Gladman (gladman) "Planetary formation at the frontiers"
Valery Milner (vmilner) "Molecular super-rotors as nanoprobes of quantum systems"
Arman Rahmim (rahmim) "Quantitative Radiomolecular Imaging & Therapy of Cancer Patients"
Allanah Hallas (hallas) "Discovery of New Quantum Materials"
Douglas Scott (dscott) "What's wrong with the Universe?"
Ziliang Ye (zlye) "2D materials - atomically thin LEGO blocks"
Mark Halpern (halpern) "Experiments to measure the dynamics of the Universe"
Sabrina Leslie "Getting a little closer to life, one molecule at a time"
Allison Man (aman) "Galaxy evolution across cosmic time"
Scott Chapman (schapman) "The most massive structures in the early Universe"
Alex Hill (ashill) "The magnetic interstellar medium"
Event Location:
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Event Time:
Thursday, September 24, 2020 | 2:00 pm - 3:00 pm
Event Location:
Zoom - TBA
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2020-09-24T14:00:00
2020-09-24T15:00:00
CM seminar - Bad Metals and Electronic Orders – Nematicity from Iron Pnictides to Moiré Systems
Event Information:
Abstract: Strongly correlated electron systems typically exhibit bad-metal behavior, which is operationally defined in terms of a resistivity at room temperature that exceeds the Mott-Ioffe-Regel limit. These systems show a rich landscape of electronic orders. Exploring this landscape is an important means to clarify the underlying microscopic physics.
Iron-based superconductors present a striking case study. They are well established to be bad metals, and their various types of electronic orders are essentially always accompanied by nematicity. In this talk, I will address the nematic aspect of this decade-old subject and summarize the effort towards a unified description of these electronic orders. A particular emphasis will be on recent studies for the intermediate-strength regime of electron correlations, including Hund’s couplings, using a variational Monte Carlo method. Implications of these results for superconductivity will be briefly discussed.
In the second part of the talk, I will consider the nematic correlations that have been observed in the graphene-based moiré narrow-band systems. I will present a recent theoretical study which demonstrates such nematicity in a ``fragile insulator”, predicts its persistence in the bad metal regime and provides a new perspective on the overall phase diagram of these systems.
Biography: Qimiao Si is the Harry C. and Olga K. Wiess Professor of Physics at Rice University and Director of Rice Center for Quantum Materials. Prior to joining Rice in 1994, he obtained a Ph.D. degree from the University of Chicago in 1991 and was a postdoctoral fellow at Rutgers University and University of Illinois at Urbana-Champaign. His major contributions have been on the theory of strongly correlated electron systems, including quantum criticality, high temperature iron-based superconductivity, and strongly correlated electronic topology. He was elected to Fellow of the American Association for the Advancement of Science, American Physical Society, and the British Institute of Physics, received a Humboldt Research Award and was selected as the 2019 Ulam Distinguished Scholar at the Los Alamos National Laboratory. He serves as a General Member on the Board of the Aspen Center for Physics.
Event Location:
Zoom - TBA
Event Time:
Monday, September 21, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-09-21T15:00:00
2020-09-21T16:00:00
The Dynamics and Origin of the Martian Moons
Event Information:
The two moons of Mars, Phobos and Deimos, have long been a mystery to astronomers. Small and irregular in shape, they are usually considered to be captured asteroids. However, their near-equatorial orbits point to their likely origin in an accretion disk around Mars. It is still not clear if these satellites were accreted from Martian debris excavated by impacts, or from material derived from captured small bodies. The Martian moons' dynamics over the age of the solar system is becoming better understood now. Phobos is interior to the synchronous orbit and its orbit is decaying; it is expected that Phobos will be disrupted into a ring by the action of Martian tidal forces in the next few tens of Myr. A crucial question about the past orbital evolution of Phobos is whether it formed close to the synchronous orbit and always migrated inward. An alternative view is that Phobos is a product of an ongoing ring-moon cycle around Mars, with past generations of inner moons being significantly more massive. I will present my recent work on the orbit of Deimos, which strongly supports the view that Mars had past rings and much larger inner moons. I will also discuss the implications for the ultimate origin of Phobos and Deimos.
Event Location:
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Event Time:
Thursday, September 17, 2020 | 3:00 pm - 5:00 pm
Event Location:
Connect to event via youtube channel
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2020-09-17T15:00:00
2020-09-17T17:00:00
Watch the Ig Nobel Prize ceremony together!
Event Information:
Connect to live video stream of ceremony through
https://www.improbable.com/ig-about/the-30th-first-annual-ig-nobel-prize-ceremony/
(or youtube channel).
And connect to local chat through the zoom link.
Event Location:
Connect to event via youtube channel
Event Time:
Thursday, September 17, 2020 | 2:00 pm - 3:00 pm
Event Location:
Zoom link - https://ubc.zoom.us/j/63429511580?pwd=S2lrY29nZ2dBRjZPWGhyeXZQSGx6dz09
Meeting ID: 634 2951 1580
Passcode: 344110
Meeting ID: 634 2951 1580
Passcode: 344110
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2020-09-17T14:00:00
2020-09-17T15:00:00
CM seminar - Orbital-selectivity and nematicity in iron-chalcogenide superconductors
Event Information:
Abstract: Electron correlation effects give rise to a variety of emergent phenomena in quantum materials-high temperature superconductivity, electronic nematicity, Mott insulating phase, and magnetism. In the multi-orbital iron-based superconductors, electronic correlations are manifested in an orbital-dependent way, realizing all of the above in different parameter regimes. In this talk, I will present experimental evidence from angle-resolved photoemission spectroscopy on systematic evolution of multi-orbital correlation effects across the iron-based superconductor material basis. In particular, I will present spectroscopic evidence for tendencies towards an orbital-selective Mott phase in Fe(Te,Se) as tuned via both temperature and isovalent substitution, as manifested in the modification of the Fermiology accompanied by the vanishing of coherent quasiparticle spectral weight and the divergence of effective mass. I will also present a connection to the role of orbitals in the nematic phase of FeSe. These exotic behaviors reveal the strong presence of correlation effects in this class of multi-orbital superconductors.
Event Location:
Zoom link - https://ubc.zoom.us/j/63429511580?pwd=S2lrY29nZ2dBRjZPWGhyeXZQSGx6dz09
Meeting ID: 634 2951 1580
Passcode: 344110
Event Time:
Thursday, September 17, 2020 | 9:00 am - 11:00 am
Event Location:
via Zoom
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2020-09-17T09:00:00
2020-09-17T11:00:00
Departmental Doctoral Oral Examination (Thesis Title: “Nuclide production and imaging applications of 225Ac for targeted alpha therapy”)
Event Information:
Departmental Doctoral Oral Examination
Thesis Abstract: <click here>
Event Location:
via Zoom
Event Time:
Monday, September 14, 2020 | 3:00 pm - 4:00 pm
Event Location:
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2020-09-14T15:00:00
2020-09-14T16:00:00
Going Non-Linear: Contrasting LCDM with observations of the internal properties of galaxies
Event Information:
The Lambda Cold Dark Matter (LCDM) paradigm has been spectacularly successful at reproducing observations of the cosmic microwave background and of the large-scale structure of the Universe. On these scales, the structures compared with the theory are in the linear or mildly non-linear regime, where observations are well established and theoretical predictions are robust. LCDM also makes specific predictions in the non-linear regime; in particular, for the abundance, structure and substructure of dark matter halos, the sites of galaxy formation. On these non-linear scales a number of potential challenges to LCDM have been identified when confronting the observed internal structure of galaxies with LCDM expectations. I plan to briefly review the status of these challenges and to discuss whether they signal a potential breakdown of the LCDM paradigm or just reflect our incomplete understanding of the complex process of galaxy formation.
Event Location:
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Event Time:
Thursday, September 10, 2020 | 4:00 pm - 5:00 pm
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2020-09-10T16:00:00
2020-09-10T17:00:00
The Latest Results from the LIGO-Virgo O3 Observing Run [CANCELLED!]
Event Information:
Unfortunately this presentation has had to be cancelled because of fires in Oregon - it will be rescheduled for some later date.
As we approach the fifth anniversary of the first detection of gravitational waves from a binary black hole merger, the LIGO and Virgo detectors have collected an impressive census of compact binary mergers in the local universe. By the end of the second observing run in August 2017 the LIGO Scientific Collaboration and Virgo Collaboration claimed a total of 10 binary black hole mergers and one binary neutron star merger. The third observing run spanned April 2019 through March 2020, during which the collaborations alerted the astronomical community of 56 merger candidates. Thus far, the exceptional events announced by the collaboration include GW190425, GW190412, GW190814, and GW190521. I will present some of what ground-based gravitational wave astronomy has taught us about compact binaries over the last five years, and what may lie ahead.
Event Location:
Connect via zoom
Event Time:
Thursday, September 10, 2020 | 2:00 pm - 3:00 pm
Event Location:
Please click the link below to join the webinar:
https://ubc.zoom.us/j/61875425478?pwd=cDNjWEN1S0lZZ1BTdEpmd3ZZNVdCdz09
Passcode: 113399
https://ubc.zoom.us/j/61875425478?pwd=cDNjWEN1S0lZZ1BTdEpmd3ZZNVdCdz09
Passcode: 113399
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2020-09-10T14:00:00
2020-09-10T15:00:00
CM seminar - Ferroelectric Superconductors
Event Information:
Abstract:
Polar superconductors have generated significant interest as a potential route to unconventional and topological superconductivity. Strained thin films of doped strontium titanate (SrTiO3) undergo successive ferroelectric and superconducting transitions. Our experimental observations of a factor of two enhancement of the superconducting transition temperature and the fact that both ferroelectricity and superconductivity vanish around the same carrier density hint at physical interactions common to both phenomena. Many different proposals of such a link have been put forward in the theoretical literature. This talk will focus on our recent insights into both the ferroelectric and superconducting states of these films. We show that the ferroelectric transition is better described as an order-disorder transition and that local polar order persists to temperatures far above the ferroelectric transition. We discuss the mechanisms by which free carriers and dopants act to suppress the ferroelectric transition. We also discuss recent insights into the nature of the superconducting state obtained via non-reciprocal transport measurements and other properties of the superconducting state.
Bio: Susanne Stemmer is Professor of Materials at the University of California, Santa Barbara. She did her doctoral work at the Max-Planck Institute for Metals Research in Stuttgart (Germany) and received her degree from the University of Stuttgart in 1995. Her research interests are in the development of scanning transmission electron microscopy techniques, molecular beam epitaxy of oxides and topological materials, strongly correlated oxide heterostructures, and topological matter. She has authored or co-authored more than 280 publications. Honors include election to Fellow of the American Ceramic Society, Fellow of the American Physical Society, Fellow of the Materials Research Society, Fellow of the Microscopy Society of America, and a Vannevar Bush Faculty Fellowship of the Department of Defense.
Event Location:
Please click the link below to join the webinar:
https://ubc.zoom.us/j/61875425478?pwd=cDNjWEN1S0lZZ1BTdEpmd3ZZNVdCdz09
Passcode: 113399