Events List for the Academic Year

Event Time: Thursday, December 6, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar 2018-12-06T16:00:00 2018-12-06T17:00:00 The human voice, the erhu and the violin Event Location: Hennings 201
Event Time: Monday, December 3, 2018 | 3:00 pm - 4:15 pm
Event Location:
Hennings 318
Add to Calendar 2018-12-03T15:00:00 2018-12-03T16:15:00 To be announced Event Information: Please join us for coffee, tea and snacks before the Colloquium in Hennings 318 at 2:45 pm Event Location: Hennings 318
Event Time: Thursday, November 29, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar 2018-11-29T16:00:00 2018-11-29T17:00:00 The Future of Cancer Medicine: Personal or Industrial? Event Location: Hennings 201
Event Time: Thursday, November 29, 2018 | 2:00 pm - 3:00 pm
Event Location:
AMPL 311
Add to Calendar 2018-11-29T14:00:00 2018-11-12T15:00:00 Moiré is Different: Wigner Solidification at Magic Angles in Doped Twisted bi-layer Graphene Event Information: In a recent paper, the MIT group led Pablo Jarillo-Herrero has found that doping twisted bi-layer graphene can generate strongly correlated insulating states and superconductivity at particular twist angles called magic angles.   This problem has excited the condensed matter community because it establishes that graphene, normally viewed as a weakly  interacting system, is a new platform for strongly correlated physics.    The experimentalists as well as a host of theorists have attributed the insulating states to Mottness.  However, this interpretation has been called into question because the simplest experimental set-up in which one charge resides in each unit cell exhibits metallic transport not Mott insulation.  I will review the experiments and 1) explain why the one-electron/unit cell case is a metal, 2) show that the insulating behaviour is consistent with a series of Wigner crystalline states that are enhanced by hydrostatic pressure as observed in the newest experiments of Dean and Young, and 3) discuss how superconductivity arises from doping  such crystalline states.   Event Location: AMPL 311
Event Time: Monday, November 26, 2018 | 3:00 pm - 4:15 pm
Event Location:
Hennings 318
Add to Calendar 2018-11-26T15:00:00 2018-11-26T16:15:00 To be announced Event Information: Please join us for coffee, tea and snacks before the Colloquium in Hennings 318 at 2:45 pm Event Location: Hennings 318
Event Time: Thursday, November 22, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar 2018-11-22T16:00:00 2018-11-22T17:00:00 Biomechanics and neural control of maneuvering flight Event Information: My research program is motivated by fascination with bird flight. My laboratory group uses a multi- disciplinary approach that includes biomechanics, physiology, and neuroscience to examine flight ability. Our current research is organized around two topics: 1) how birds morph their wings and what benefits this provides; and 2) how optic flow signals are encoded in the avian brain and used to guide their flight. As we gain understanding of flight mechanisms, we further endeavor to apply comparative approaches that provide deeper insight into avian ecology and evolution. Event Location: Hennings 201
Event Time: Thursday, November 22, 2018 | 2:00 pm - 3:00 pm
Event Location:
BRIM 311
Add to Calendar 2018-11-22T14:00:00 2018-11-22T15:00:00 TBA Event Location: BRIM 311
Event Time: Monday, November 19, 2018 | 3:00 pm - 4:15 pm
Event Location:
Hennings 318
Add to Calendar 2018-11-19T15:00:00 2018-11-19T16:15:00 To be announced Event Information: Please join us before the Colloquium in Hennings 318 for coffee, tea and snacks at 2:45 pm Event Location: Hennings 318
Event Time: Monday, November 19, 2018 | 1:00 pm - 2:00 pm
Event Location:
TRIUMF Conference Room
Add to Calendar 2018-11-19T13:00:00 2018-11-19T14:00:00 Cosmology with Massive Neutrinos Event Information: The non-zero mass of neutrinos suppresses the growth of cosmic structure on small scales. Since the level of suppression depends on the sum of the masses of the three active neutrino species, the evolution of large-scale structure is a promising tool to constrain the total mass of neutrinos and possibly shed light on the mass hierarchy. I will discuss recent progress and future prospects to constrain the neutrino mass sum with cosmology. Event Location: TRIUMF Conference Room
Event Time: Friday, November 16, 2018 | 12:30 pm - 2:30 pm
Event Location:
Room 488, The Brimacombe Building, 2355 East Mall
Add to Calendar 2018-11-16T12:30:00 2018-11-16T14:30:00 Final PhD Oral Examination (Thesis Title: “Peierls Bipolarons and Localization in Solid-State and Molecular Systems") Event Information: Thesis Abstract:In this thesis, I investigate the behavior of particles dressed by quantum field excitations and random interactions. First I consider two-carrier states in the Peierls model describing the modulation of the particle hopping due to lattice distortions. I compute the spectral response using the Momentum Average approximation. Combining accurate numerical techniques and analytical arguments, I provide a complete picture of the Peierls bipolarons. It is found that polarons bind into strongly bound yet light bipolarons in the singlet sector, even at large values of the electron-phonon coupling strength. At finite electron fillings, these bipolarons may condense into a high-Tc superconductor. On the other hand, phonons mediate a repulsive interaction in the triplet sector, or equivalently (in one dimension), between two hard-core particles. In this case, the ground-state dimers bound by sufficiently attractive bare interactions exhibit two sharp transitions, one of which is the first known example of a self-trapping transition at the two-carrier level. In both cases, phonons mediate unusual pair-hopping effective interactions between the carriers. I further study some aspects of the excited spectrum for the two hard-core particles, a situation relevant to ultracold quantum simulators. It is found that the repulsive phonon-mediated interaction binds a repulsive bipolaron embedded in the excited spectrum. I then turn to the study of quenched randomness in an ultracold molecular plasma. I argue that the quenched ultracold plasma presents an experimental platform for studying quantum many-body physics of disordered systems in the long-time and finite energy-density limits. I analyze an experiment that quenches a plasma of nitric oxide to an ultracold system of Rydberg molecules, ions and electrons that exhibits a long-lived state of arrested relaxation. The qualitative features of this state fail to conform with classical models. I develop a microscopic quantum description for the arrested phase based on an effective many-body spin Hamiltonian that includes both dipole-dipole and van der Waals interactions. This effective model appears to offer a way to envision the essential quantum disordered non-equilibrium physics of this system. This thesis thus examines the quantum many-body response in interacting systems coupled to bosonic fields or in disordered environments. Event Location: Room 488, The Brimacombe Building, 2355 East Mall
Event Time: Friday, November 16, 2018 | 10:00 am - 11:00 am
Event Location:
BRIM 311
Add to Calendar 2018-11-16T10:00:00 2018-11-16T11:00:00 TBA Event Location: BRIM 311
Event Time: Thursday, November 15, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar 2018-11-15T16:00:00 2018-11-15T17:00:00 Feeling the strain: fields for electronic nematic order Event Information: It is common to think of strains in solids in a somewhat passive sense, simply as the response of a material to external forces. However, for certain types of electronic order, strains of a specific symmetry can have much more important roles to play, acting as longitudinal, and even transverse, fields for the order parameter. In this talk, I will first describe how antisymmetric strain can act as a longitudinal field for electronic nematic order. I'll then go on to describe appropriate transverse fields for nematic order, including orthogonal antisymmetric strain, illustrating these points with various materials. Using such effects it becomes possible to tune materials that exhibit electronic nematic order towards a quantum phase transition. I'll explain why this is such an exciting prospect. Event Location: Hennings 201
Event Time: Wednesday, November 14, 2018 | 7:30 pm - 9:00 pm
Event Location:
Earth Sciences Building - RM 1013 (2207 Main Mall) UBC
Add to Calendar 2018-11-14T19:30:00 2018-11-14T21:00:00 Are We Quantum Brains, or Merely Clever Robots? Event Information: The effort to design and build quantum computers in the laboratory is now a billion dollar enterprise. But might we, ourselves, be quantum computers? Most scientists think that in the warm wet brain, this is highly unlikely; and certainly it would be at variance with what the medical profession believes. My strategy is one of reverse engineering, seeking to identify the biochemical substrate and mechanisms that could host such putative quantum processing. Remarkably, a specific neural qubit and a unique collection of ions, molecules and enzymes can be identified, illuminating an apparently single path towards nuclear spin quantum processing in the brain. If this is true, the implications for medicine and psychiatry would be very large. Event Location: Earth Sciences Building - RM 1013 (2207 Main Mall) UBC
Event Time: Wednesday, November 14, 2018 | 1:00 pm - 2:00 pm
Event Location:
Henn room 318, 6224 Agricultural Road
Add to Calendar 2018-11-14T13:00:00 2018-11-14T14:00:00 Extreme fine-tuning of the cosmological constant is not needed Event Information: We show that when the bare cosmological constant in the Einstein field equations takes large negative values, the average distance between any two nearby geodesics moving in the spacetime sourced by quantum fields vacuum would gradually increase at a slow accelerating rate due to the weak parametric resonance effect caused by the fluctuations of the quantum vacuum energy density. In this scenario, the extreme fine-tuning of the cosmological constant is not needed. This resolves the cosmological constant problem and provides an explanation to the accelerating expansion of our universe. Event Location: Henn room 318, 6224 Agricultural Road
Event Time: Monday, November 12, 2018 | 3:00 pm - 4:15 pm
Event Location:
Where you choose to observe
Add to Calendar 2018-11-12T15:00:00 2018-11-12T16:15:00 REMEMBRANCE DAY OBSERVANCE - No Astronomy Colloquium today Event Location: Where you choose to observe
Event Time: Thursday, November 8, 2018 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
Add to Calendar 2018-11-08T16:00:00 2018-11-08T17:00:00 Soft Materials at surfaces and interfaces: Elastocapillarity Event Information: The physics of soft materials is distinct from hard matter, as the weaker intermolecular bonds can result in a large response to external stresses. In recent years, there has been a significant interest in understanding the interaction between a liquid’s surface tension and a solid’s elasticity: elastocapillarity. In particular, liquids can generate significant deformations of highly compliant materials. These elastocapillary interactions are highly relevant in a wide variety of systems including capillary origami, kirigami, and folding, soft tissues, wetting of fibers and hair, and micro-patterning of soft surfaces. In this talk I will summarize our recent work on the capillary interactions of liquid droplets with elastic surfaces. Event Location: Hennings 201
Event Time: Thursday, November 8, 2018 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar 2018-11-08T14:00:00 2018-11-08T15:00:00 Unification from Scattering Amplitudes Event Information: Scattering amplitudes are fundamental observables that encode the dynamics of interacting particles. In this talk, I describe how to systematically construct these objects without reference to a Lagrangian or an underlying spacetime. The physics of real-world particles like gravitons, gluons, and pions are thus derived from the properties of amplitudes rather than vice versa. Remarkably, the expressions gleaned from this line of attack are marvelously simple, revealing new structures long hidden in plain sight. As an example, I describe how gravitons are in a very precise way equivalent to products of gluons - a fact with far-reaching theoretical and phenomenological applications. Lastly, I show how gravity serves as the "mother of all theories" whose amplitudes secretly unify, among others, all gluon and pion amplitudes. Event Location: TRIUMF Auditorium
Event Time: Monday, November 5, 2018 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
Add to Calendar 2018-11-05T15:00:00 2018-11-05T16:00:00 A machine-learning view of our Milky Way Event Information: Every night, telescopes around the world obtain a flood of new data as parts of deep and wide surveys. This amount of data will steeply rise once upcoming sureys such as the Large Synoptic Survey Telescope (LSST), which will image the entire visible sky every few nights, start their operation. To investigate this huge amount of data, machine-learning algorithms are absolutely necessary for image analysis, classification of sources, time-series analysis and also structure finding. Using the example of the Pan-STARRS1 3pi survey as a deep panoptic high-latitude survey in the time domain, in this talk it will be shown how to explore the capabilities of such surveys for carrying out time-domain science in a variety of applications. We use structure-function fitting, period fitting and subsequent machine-learning classification to search for and classify high-latitude as well as low-latitude variable sources, in particular RR Lyraes, Cepheids and QSOs. Our further analysis reveals the extent of the Sagittarius stream as well as other overdensities in the Milky Way's outer halo. In addition, it will be shown how carefully chosen follow-up observations can support large surveys, such as Pan-STARRS1 3pi, and our goal of investigating the structure of the Milky Way's halo. Please join us before the Colloquium in Hennings 318 for coffee, tea and snacks at 2:45 pm Event Location: Hennings 318
Event Time: Monday, November 5, 2018 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
Add to Calendar 2018-11-05T14:00:00 2018-11-05T15:00:00 Neutrino Interferometry at DUNE: Preparing for the Deep Underground Neutrino Experiment Event Information: The fact that neutrinos have mass and change flavors means that we can learn a great deal about them by studying what are effectively interference patterns that arise after neutrinos propagate over hundreds of kilometers. The DUNE experiment will measure these interference patterns over a broad neutrino energy range after neutrinos have propagated 1300km. In addition, DUNE will use a detector technology that provides exquisite detail about the interactions that make up the interference pattern. This talk will present the current state of neutrino interference measurements and the various ways the field is preparing to jump to a new level of understanding. Event Location: TRIUMF Auditorium
Event Time: Monday, November 5, 2018 | 12:00 pm - 2:00 pm
Event Location:
Room 309, Hennings Building
Add to Calendar 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