Events List for the Academic Year
Event Time:
Monday, November 5, 2018 | 12:00 pm - 2:00 pm
Event Location:
Room 309, Hennings Building
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2018-11-05T12:00:00
2018-11-05T14:00:00
Departmental Oral Examination (Thesis Title: “Modelling exciton dynamics in light-harvesting molecules”)
Event Information:
I investigate the dynamics of multi-state central systems coupled bilinearly to an external oscillator bath within the noninteracting-blip approximation. I focus on both a 3-site configuration, as well as a 2-site model for the central systems of interest.
Both diagonal and non-diagonal system-bath couplings are considered, and for the case of the 2-site central system, a dual coupling approach is taken. The bath spectral densities considered in this work include both Ohmic and super-Ohmic forms as well as single optical phonon peaks. This work is motivated by the recent observance of long-lived quantum coherence effects in the photosynthetic organism known as the Fenna-Matthews-Olson complex.
The models investigated in this thesis are applied to this system in an attempt to reproduce the experimentally observed coherence times, and potentially explain the underlying physical mechanisms responsible for these observations. The dual-coupling-2-site model is shown to reproduce the relatively long coherence times observed in the Fenna-Matthews-Olson complex remarkably well. The non-diagonal system-bath coupling is shown to play a crucial role in this process, not only increasing the decoherence times in the system, but also increasing the dimer oscillation frequency in accordance with the well-known phonon-assisted transfer mechanism. These findings suggest that the physical mechanism responsible for the observed quantum-coherence effects in photosynthesis might be the presence of non-diagonal system-bath couplings.
Event Location:
Room 309, Hennings Building
Event Time:
Thursday, November 1, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2018-11-01T16:00:00
2018-11-01T17:00:00
Atoms in Cavities
Event Information:
Physicists have been exploring techniques for the controlled manipulation of large collections of quantum objects. A valuable strategy has been placing collections of laser-cooled atoms in optical cavities. I will review the state of the field, some of the underlying physics, and the outlook.
Event Location:
Hennings 201
Event Time:
Monday, October 29, 2018 | 3:00 pm - 4:15 pm
Event Location:
Hennings 318
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2018-10-29T15:00:00
2018-10-29T16:15:00
Dark Matter and the Dance of Dwarf Galaxies
Event Information:
Major galaxies such as the Milky Way are surrounded by swarms of smaller dwarf satellite galaxies. Over the past 15 years, our knowledge of these satellite galaxies has exploded. The number of known Milky Way satellites has quadrupled, and highly precise measurements of their motions, with the Hubble Space Telescope and most recently with Gaia, have provided unprecedented insights into their complex orbital dance. I will talk about my work that uses the distribution and motion of satellite galaxies to test our ideas of how the cosmos in general, and galaxies in particular, have formed and evolved. Our current leading cosmological model, LCDM, was largely developed on cosmic scales and implies that most of the mass in the Universe is dominated by Cold Dark Matter. Simulations of the formation and evolution of galaxies based on this model predict a highly chaotic tangle of satellite dwarf galaxies around their more massive hosts. In contrast, my research finds that the observed situation resembles an ordered choreography: the satellite galaxies around the Milky Way, Andromeda, and Centaurus A are aligned along so-called “planes of satellite galaxies”. Many satellites also move along these structures in a common direction. I will discuss why this finding poses a serious challenge to our leading model of cosmology, whether there is evidence that the inclusion of baryonic processes in simulations can alleviate the existing tension, and why all suggested scenarios for their formation are currently unable to solve the issue.
Please join us before the Colloquium in Hennings 318 for coffee, tea and snacks at 2:45 pm
Event Location:
Hennings 318
Event Time:
Friday, October 26, 2018 | 12:30 pm - 5:00 pm
Event Location:
Hennings 318
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2018-10-26T12:30:00
2018-10-26T17:00:00
Equity and Inclusion Open House
Event Information:
What is the Equity and Inclusion in PHAS group? Come to our open house to learn about our mission, what we are doing to help promote opportunities for our community, how to get involved, and learn about equity issues. We are offering a lunch and poster session to mingle with everyone in our department to engage in the conversation around equity, inclusion and diversity.
In the afternoon we invite you to attend our workshops to learn techniques for being an ally to underrepresented members of our community and tools for improving your wellness as you advance in your scientific career (more information below).
We are celebrating our first year anniversary since our founding, so join us for a piece of cake to end the week!
Come and go as you please throughout the event! We can’t wait to see you there!
For more information visit https://equity-inclusion.phas.ubc.ca/2018/09/21/open-house/
Event Location:
Hennings 318
Event Time:
Thursday, October 25, 2018 | 4:00 pm - 6:00 pm
Event Location:
Hennings 201
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2018-10-25T16:00:00
2018-10-25T18:00:00
Excited-State Dynamics and Quantum Interaction from First Principles
Event Location:
Hennings 201
Event Time:
Thursday, October 25, 2018 | 2:00 pm - 3:00 pm
Event Location:
AMPL 311
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2018-10-25T14:00:00
2018-10-25T15:00:00
Linear-, Nonlinear- and Hydrodynamics in Quantum Materials.
Event Information:
Today, we imagine a world where we can engineer materials and devices atom-by-atom. Exciting discoveries during the past few decades in quantum science and technology have brought us to this next step in the quantum revolution: the ability to fabricate, image and measure materials and their properties at the level of single atoms is almost within our grasp. Yet, at the most fundamental level a tractable quantum mechanical description and understanding of these materials does not exist. The physics of quantum materials is rich with spectacular excited-state and non-equilibrium effects, but many of these phenomena remain poorly understood and consequently technologically unexplored. Therefore, my research focuses on understanding how quantum-engineered materials behave, particularly away from equilibrium, and how we can harness these effects for technologies of the future. I will present my approach, from a theoretical and computational standpoint, in this seminar. I will show recent results using newly developed theoretical methods to evaluate the linear optical properties of low dimensional and heterostructured quantum materials. Further I will discuss how we extend these methods as a computational probe of hydrodynamic materials, for which electronic transport behaves according to the laws of hydrodynamics over conventional scattering descriptions. Finally, I will show the linear and nonlinear optical properties of these hydrodynamic and other similar Dirac and Weyl compounds to better understand the effect of linear dispersion on overall transport and optical properties.
Event Location:
AMPL 311
Event Time:
Wednesday, October 24, 2018 | 1:00 pm - 2:00 pm
Event Location:
Henn 318
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2018-10-24T13:00:00
2018-10-24T14:00:00
Instabilities of charged black holes and small hairy black holes
Event Information:
Reissner-Nordstrom black holes (RN BH) in AdS suffer from two linear instabilities, superradiance and the near horizon instability. The endpoint of these instabilities is a hairy black hole. I will present an analytic perturbative construction of these hairy black holes and analyse the phase space of solutions. In asymptotically flat spacetime, inspired by the black hole bomb of Press and Teukolsky, one can surround a RN BH by a reflecting box. It is known that this system suffers from superradiant instability. We show that the near horizon instability is also present there. As in the AdS case, the endpoint is a hairy black hole that we construct analytically in a perturbative expansion. We comment on the matter content of the box.
Event Location:
Henn 318
Event Time:
Monday, October 22, 2018 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2018-10-22T15:00:00
2018-10-22T16:00:00
Ten Thousand Pieces of Blue Sky: Building towards the complete picture of exoplanet demographics
Event Information:
Please join us before the Colloquium in Hennings 318 for coffee, tea and snacks at 2:45 pm
The NASA Kepler mission has provided its final planet candidate catalogue, the K2 mission has contributed another four years’ worth of data, and the NASA TESS mission has just started producing planet candidates of its own. The demographics of the exoplanet systems probed by these transiting exoplanet missions are complemented by the demographics probed by other techniques, including radial velocity, microlensing, and direct imaging. I will walk through the progress of the Kepler occurrence rate calculations, including some of the outstanding issues that are being tackled. I will demonstrate how K2 and TESS are able to push the stellar parameter space in which we can explore occurrence rates beyond that examined by Kepler, and progress to that end. Finally, I will highlight some of the pieces of the larger demographics puzzle - occurrence rate results from the other techniques that probe different stellar and exoplanet regimes - and how we can start joining those pieces together.
Event Location:
Hennings 318
Event Time:
Friday, October 19, 2018 | 10:00 am - 11:00 pm
Event Location:
Life 2602
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2018-10-19T10:00:00
2018-10-19T23:00:00
Exploring Rates of Change in Calculus and Upper-Level Physics Courses
Event Information:
Physics is the study of change. In many cases, this change involves more than one independent and one dependent physical quantity. In these cases the partial derivative is an important tool, including the geometric combinations of partial derivatives in E & M (e.g. gradient) and the measurable combinations in thermodynamics (e.g. heat capacity). These applications required students to have rich concept images of partial derivatives which go well beyond what is typically taught in a multivariable calculus course, particularly concepts which deal with data and experimental representations. Using a mixed workshop/talk format, participants will explore examples of instructional materials designed to foster improved learning of partial derivatives concepts and experience innovative hands-on tools, such as the partial derivative machine and two dimensional dry erasable plastic surfaces. We also describe key aspects of our research to understand how students interact with these materials. This work was supported in part by NSF grant DUE-1323800.
Event Location:
Life 2602
Event Time:
Thursday, October 18, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2018-10-18T16:00:00
2018-10-18T17:00:00
Occam's Razor and Climate Change: How to Explain Climate Change to Non-Scientists
Event Location:
Hennings 201
Event Time:
Thursday, October 18, 2018 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
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2018-10-18T14:00:00
2018-10-18T15:00:00
A tabletop-scale probe for TeV physics: the electric dipole moment of the electron
Event Information:
Time-reversal (T) symmetry is observed to be broken in K- and B-meson systems, in a manner consistent with the Standard Model (SM) of electroweak interactions. Violation of T-invariance makes it possible for elementary particles such as the electron to have an electric dipole moment (EDM) along their spin axis. Although the SM prediction for the electron EDM is too small to detect, extensions to the SM frequently predict EDMs within a few orders of magnitude of the current limits. I will describe our ACME experiment, which uses methods of atomic and molecular physics to detect the electron's EDM. We recently completed the most sensitive search for this quantity, finding a result consistent with zero but setting a limit an order of magnitude smaller than previous work. Remarkably, the result of this tabletop-scale experiment sets strong constraints on the existence of T-violating phenomena well above the TeV scale being probed at the Large Hadron Collider, and has a substantial impact on theories of physics beyond the Standard Model.
Remote connection link:
https://mediasite.audiovisual.ubc.ca/Mediasite/Catalog/catalogs/triumf_colloquium
Event Location:
TRIUMF Auditorium
Event Time:
Thursday, October 18, 2018 | 2:00 pm - 3:00 pm
Event Location:
AMPEL 311
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2018-10-18T14:00:00
2018-10-18T15:00:00
Prof. Joe Trodahl from MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington
Event Information:
Controlling the flow of electronic spin in addition to the charge promises speed and power demand advantages. However, there are as yet few “spintronic” devices on the market, in part due to a lack of intrinsic ferromagnetic semiconductors that would permit full exploitation of the coupled spin/charge technology. To date the only full series of such materials are the mononitrides of the lanthanides, the 14 rare-earth elements. Many of the LN (L a lanthanide element) are intrinsic ferromagnetic dopable semiconductors, with strongly contrasting magnetic properties which result from the coupled spin and orbital moments residing in the lanthanide 4f shells.[1] We started investigating epitaxial and polycrystalline film growth and electronic-magnetic properties of these compounds a decade ago, motivated by a prediction of half metals among their number,[2] only to discover their semiconducting nature. In the past few years we began work on LN/L’N heterostructures including tunnelling structures.[3] Furthermore we have investigated integration with both the optical III-V semiconductors and superconductors of interest for their potential in central processors. Along the way there have been many surprises, most recently that one of the series, near-zero-magnetisation ferromagnetic SmN, is superconducting below 4 K.[4] Even more recently an investigation of the carrier-concentration dependence of the anomalous Hall effect in these materials has provided a clear quantitative theory of their intrinsic Berry-phase anomalous Hall effect.[5] The talk will cover the lot, the growth conditions and crystal structure, control of their carrier concentration, investigations of their coupled magnetic/electronic properties, tunnelling in device-like structures and the observation of the remarkable superconductivity in doped SmN.
[1] F. Natali et al., Prog. Materials Science 58, 1316 (2013).
[2] C. M. Aerts et al., Phys. Rev. B 69, 045115 2004.
[3] H. Warring et al., Phys. Rev. Appl. 6, 044002 (2016).
[4] E.-M. Anton et al., Phys. Rev. B 94, 024106 (2016).
[5] H.J. Trodahl et al., Phys. Rev. B 96, 115309 (2017).
Event Location:
AMPEL 311
Event Time:
Thursday, October 18, 2018 | 12:45 pm - 1:45 pm
Event Location:
Henn 318
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2018-10-18T12:45:00
2018-10-18T13:45:00
A Flexible New Teaching Technology for Facilitating Peer Evaluation: The ComPAIR Project at UBC
Event Information:
We introduce ComPAIR, an open source, peer feedback and teaching technology developed at UBC that provides students a safe, flexible environment to develop the skill of evaluating another person’s work, and in turn, receive evaluations from their peers. ComPAIR is currently being used by about 40 courses here at UBC and has been installed at three external institutions. Particularly in introductory courses, the effectiveness of peer feedback can be limited by the relative newness of students to both the course content and the skills involved in providing good feedback. ComPAIR makes use of students’ inherent ability and desire to compare: according to the psychological principle of comparative judgement, novices are much better at choosing the “better” of two answers than they are at giving those answers an absolute score. By scaffolding peer feedback through comparisons, ComPAIR provides an engaging, simple, and safe environment that supports two distinct outcomes: 1) students learn how to assess their own work and that of others in a way that 2) facilitates the learning of subtle aspects of course content through the act of comparing. The presentation will focus on the usage of ComPAIR in the classroom. What kind of assignments work well? What does student workflow look like? What does the instructor workflow look like? You'll also have the opportunity to use the software from the perspective of an instructor, course administrator, and student.
This talk is part of the Physics and Astronomy Education Group's brown-bag teaching series. Please feel free to bring your lunch. Coffee and cookies will be provided.
Event Location:
Henn 318
Event Time:
Tuesday, October 16, 2018 | 12:45 pm - 2:45 pm
Event Location:
Room B319, Buchanan Building Block B
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2018-10-16T12:45:00
2018-10-16T14:45:00
Final PhD Oral Examination (Thesis Title: “Orbital outcomes of STIPs and consequences for hot-Jupiter formation and planet diversity”)
Event Information:
(please check this link)
Event Location:
Room B319, Buchanan Building Block B
Event Time:
Monday, October 15, 2018 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2018-10-15T15:00:00
2018-10-15T16:00:00
The Life Cycle of Nearby Galaxies: internal and external processes regulating their gas content
Event Information:
Every star in our Milky Way, and in all other galaxies, was born from the collapse of a cloud of hydrogen gas. The importance of cold gas in galaxy evolution is therefore well established, as is its role as a probe of recent environmental effects on galaxies. However, sensitivity limitations mean the extent to which internal and external processes drive variations in the gas-star formation cycle of galaxies remains unclear. In this talk I will show how we take full advantage of the powerful atomic hydrogen spectral stacking technique to overcome this obstacle and provide strong observational evidence of significant and systematic environment-driven gas stripping across the group regime, well before galaxies enter the cluster. This was accomplished using the largest sample of atomic gas and multi-wavelength information then available (28,000 galaxies), selected according to stellar mass (M*>10^9 Msol) and redshift (0.02 < z < 0.05) only. Finally, I will show how state-of-the-art observations of molecular gas in local ultra-luminous infrared galaxies can be used to test if the star-formation process (and the initial distribution of stellar masses) differs fundamentally between galaxies.
Event Location:
Hennings 318
Event Time:
Monday, October 15, 2018 | 12:30 pm - 1:30 pm
Event Location:
Henn 309
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2018-10-15T12:30:00
2018-10-15T13:30:00
Determining the atomic excited-state fraction in a magneto-optical trap
Event Information:
This talk introduces an empirical method for determining the excited-state fraction of atoms in a magneto-optical trap (MOT). The four-level theoretical model was verified experimentally for atoms in a MOT, and two experimental saturation parameters were extracted from the model to estimate the excited-state fraction as a function of the MOT trap parameters. This type of measurement is essential for the use of cold atoms as a sensor when they are held in a MOT since their interactions with other particles and fields is quantum state dependent. We plan to use this method to distinguish the ground and excited state collision cross section of Rb atoms with species in residual gas of the vacuum. This is the first step to establishing atom loss rates from a MOT as an atomic primary pressure standard.
Event Location:
Henn 309
Event Time:
Thursday, October 11, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2018-10-11T16:00:00
2018-10-11T17:00:00
Short-Baseline Neutrino Anomalies and the Evidence for Sterile Neutrinos
Event Information:
The LSND and MiniBooNE short-baseline neutrino experiments have provided evidence for neutrino oscillations at a mass scale of approximately 1 eV. When combined with oscillation measurements at the solar and atmospheric mass scales, these experiments imply the existence of more than three neutrino mass states and, therefore, one or more "sterile" neutrinos. Such sterile neutrinos, if proven to exist, would have a big impact on particle physics, nuclear physics, and astrophysics, and would contribute to the dark matter of the Universe. The ongoing Short-Baseline Neutrino (SBN) program at Fermilab will provide a definitive test of short-baseline neutrino oscillations and will have the capability of proving the existence of sterile neutrinos.
Event Location:
Hennings 201
Event Time:
Thursday, October 11, 2018 | 2:00 pm - 3:00 pm
Event Location:
AMPL 311
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2018-10-11T14:00:00
2018-10-11T15:00:00
Microwave signatures of Z2 and Z4 fractional Josephson effects
Event Information:
Fractional Josephson effects comprise some of the main signatures of topological features and quasi-particle fractionalization in Josephson junctions.
With the goal of better understanding the effects of interactions, as well as of developing new methodologies for extracting such topological information from Josephson junctions, we present a many-body exact diagonalization study of the Z2 and Z4 Josephson effects in circuit quantum electrodynamics architectures. After an introduction to the rich phenomenology of these Josephson effects, I will present numerical simulations conducted on Kitaev
chain Josephson junctions hosting nearest-neighbour Coulomb interactions.
The low-energy effective theory of highly transparent Kitaev chain junctions is shown to be identical to that of junctions
created at the edge of a quantum spin-Hall insulator. By capacitively coupling the interacting junction to a microwave resonator, we predict signatures of the fractional Josephson effects on the cavity frequency and on time-resolved reflectivity measurements.
Event Location:
AMPL 311
Event Time:
Wednesday, October 10, 2018 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
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2018-10-10T14:00:00
2018-10-10T15:00:00
Significant Excess of Electron-Like Events in MiniBooNE
Event Information:
The MiniBooNE experiment at Fermilab observes an excess of 460.5+-99.0 nue CCQE candidate events in the 200 < E < 1250 MeV energy range, corresponding to a significance of 4.7 sigma. If interpreted in a two-neutrino oscillation model, numu -> nue, the best oscillation fit to the excess has a probability of 21.1%, while the background-only fit has a chisquare probability of 6E-7 relative to the best fit. The MiniBooNE data are consistent in energy and magnitude with the excess events observed by the LSND experiment. Although the data are fit with a two-neutrino oscillation model, other models may provide better fits to the data.
Event Location:
TRIUMF Auditorium
Event Time:
Monday, October 8, 2018 | 3:00 pm - 4:15 pm
Event Location:
Stay home if you can
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2018-10-08T15:00:00
2018-10-08T16:15:00
THANKSGIVING HOLIDAY - No Astronomy Colloquium today
Event Information:
There will be no turkey dinner in Hennings 318. Sorry.
Event Location:
Stay home if you can