Events List for the Academic Year
Event Time:
Monday, February 25, 2019 | 11:00 am - 12:30 pm
Event Location:
Henn 318
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2019-02-25T11:00:00
2019-02-25T12:30:00
Searching for light dark matter with single-phonon detectors
Event Information:
Searches for high energy signatures from beyond the standard model physics have advanced greatly, but a lot of ground remains to be covered for soft, low energy signals. In the context of dark matter direct detection, future single-phonon detectors will be sensitive to dark matter with a mass as low as roughly 10 keV. In this regime, the conventional nuclear recoil picture no longer applies and new theoretical tools are needed to correctly calculate the scattering rate. I will discuss the prospects for detector concepts based on superfluid helium and polar material targets, where in the latter case we find a large daily modulation of the scattering rate.
Event Location:
Henn 318
Event Time:
Thursday, February 21, 2019 | 2:00 pm - 2:00 pm
Event Location:
TRIUMF Auditorium
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2019-02-21T14:00:00
2019-02-21T14:00:00
Physics with bubble chambers
Event Information:
Bubble chambers have a long history of use in particle physics, starting with being used for particle discovery in the 1950s and moving through to their use in dark matter search experiments today. The many different target fluids which have been used have provided great flexibility in the use of this technology. In this talk I will start with a very brief history of these detectors and quickly move on to their use in the PICO experiment. After discussion of the stages and plans for that collaboration, a possibility of future improvements to the bubble chamber will be presented.
Remote link:
https://mediasite.audiovisual.ubc.ca/Mediasite/Play/3203f194c1f64086abd66af97756f23a1d
Event Location:
TRIUMF Auditorium
Event Time:
Thursday, February 14, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2019-02-14T16:00:00
2019-02-14T17:00:00
3-minute thesis talks
Event Information:
Please come and support our students as they give 3-minute presentations of their thesis projects, as part of the international "3MT" competition!
Event Location:
Hennings 201
Event Time:
Thursday, February 14, 2019 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
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2019-02-14T14:00:00
2019-02-14T15:00:00
Gamma-ray spectroscopy with GRETINA at NSCL
Event Information:
The gamma-ray tracking array GRETINA has completed a variety of experiments at the National Superconducting Cyclotron Laboratory at Michigan State University. An overview will be presented, showing selected results covering broad topics from nuclear structure physics to nuclear astrophysics.
Event Location:
TRIUMF Auditorium
Event Time:
Thursday, February 14, 2019 | 2:00 pm - 3:30 pm
Event Location:
BRIM 311
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2019-02-14T14:00:00
2019-02-14T15:30:00
CM Seminar: Signatures of dispersing Majorana modes in a proximitized topological material
Event Information:
Majorana fermions can be realized as quasiparticle excitations in a topological superconductor, whose non-Abelian statistics provide a route to developing robust qubits. In this context, there has been a recent surge of interest in the iron-based superconductor, FeSe0.5Te0.5. Theoretical calculations have shown that FeSe0.5Te0.5 may have an inverted band structure which may lead to topological surface states, which can in turn host Majorana modes under certain conditions in the superconducting phase. Furthermore, recent STM studies have demonstrated the existence of zero-bias bound states inside vortex cores which have been interpreted as signatures of Majorana modes. While most recent studies have focused on Majorana bound states, more generally, akin to elementary particles, Majorana fermions can propagate and display linear dispersion. These excitations have not yet been directly observed, and can also be used for quantum information processing. This talk is focused on our recent work in realizing dispersing Majorana modes. I will describe the conditions under which such states can be realized in condensed matter systems and what their signatures are. Finally, I will describe our scanning tunneling experiments of domain walls in the superconductor FeSe0.45Te0.55, which might potentially be first realization of dispersing Majorana states in 1D.
Event Location:
BRIM 311
Event Time:
Monday, February 11, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2019-02-11T15:00:00
2019-02-11T16:00:00
Why you should care about white dwarf stars
Event Information:
More than 95% of the stars in the Universe will eventually end up as white dwarf stars. Although they are currently more numerous than all the stars with 1 solar mass and above combined, they receive a relatively small share of the astronomical community attention (unless they happen to explode as a type Ia supernova). Yet, these fascinating objects have a lot to teach us about stellar evolution, planets, fundamental physics and much more. In this presentation, I will review some of most interesting topics that my group and I have recently investigated and try to convince you that they are more than just boring little dim objects.
Event Location:
Hennings 318
Event Time:
Thursday, February 7, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2019-02-07T16:00:00
2019-02-07T17:00:00
A Physicist's Guide to Software Engineering Jobs
Event Information:
I was a physics/math major at UBC and spent 7 years doing cosmology research before joining Google in 2015 to work as a software engineer. I'll try to summarize the career wisdom I picked up along the way, give advice on how to get a job as a software engineer, and paint a picture of daily life working for a large internet company with a goofy name. I'll also give an overview of the sorts of problems software engineers get to tackle, and how they compare to the problems you get to work on in P&A.
Event Location:
Hennings 201
Event Time:
Thursday, February 7, 2019 | 2:00 pm - 3:00 pm
Event Location:
TRIUMF Auditorium
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2019-02-07T14:00:00
2019-02-07T15:00:00
What is the Dark Matter?
Event Information:
Four fifths of the matter in the universe consist of something completely different from the "ordinary matter" we know and love. I will explain why this "dark matter" is an unavoidable ingredient to understand the universe as we observe it, and I will describe what the fundamental, particle nature of the dark matter could possibly be. I will then give an overview of strategies to search for dark matter as a particle, describe a few examples of possible hints of discovery, and outline ways forward in this exciting hunt.
Event Location:
TRIUMF Auditorium
Event Time:
Thursday, February 7, 2019 | 2:00 pm - 3:00 pm
Event Location:
BRIM 311
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2019-02-07T14:00:00
2019-02-07T15:00:00
CM Seminar: Many body entanglement, strange metals and black holes
Event Information:
It may well be that mankind has understood only the tip of the iceberg when it comes to the nature of matter. Densely many body entangled compressible states of matter may exist exhibiting entirely different physical behaviors compared to the "classical" short ranged entangled product state stuffs from the high energy- and condensed matter textbooks. Although not computable directly - a quantum computer is required - a remarkable confluence occurred in theoretical physics involving empirical notions from condensed matter physics merging with the holographic duality of string theory, and notions of quantum information. This theoretical development suggests universal principles of a new kind to be at work. As a common denominator, these suggest paradoxically that observable properties may be unreasonably simple. I will highlight some very recent experimental developments both in the Netherlands and Stanford aimed at finding out whether such principles are actually the secret behind the long standing mysteries revealed by condensed matter experimentation in especially the cuprate superconductors.
Event Location:
BRIM 311
Event Time:
Monday, February 4, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2019-02-04T15:00:00
2019-02-04T16:00:00
Insights into dark matter from the stellar halos of galaxies
Event Information:
Cosmological simulations can now make specific and detailed predictions for the shapes, masses, and substructure fractions in galactic dark matter halos: predictions that depend on the dark matter model assumed. Comparing these predictions to the observed mass distributions of galaxies should in principle lead to constraints on the nature of dark matter, but observable dynamical tracers can be scarce in regions where the dark matter distribution is best able to discriminate between models. One such region is the distant outskirts of galaxies, where the influence of baryonic matter on the dark matter halo is limited and the effect of dark substructures most prominent. New surveys of Milky Way stars like Gaia, alongside next-generation instruments and giant telescopes, are for the first time providing accurate positions, velocities, and abundances for large numbers of stars in faint tidal streams: remnants of tidally-disrupted satellite galaxies that trace out the mass distribution in the distant reaches of galaxy halos. I will show how state-of-the-art simulations play a crucial role in interpreting and analyzing this wealth of new information about stellar halos, and how stellar halo observations over the next decade will characterize the dark matter distribution in galaxies, test theories of the nature of dark matter, and illuminate the role of dark matter in galaxy formation.
Event Location:
Hennings 318
Event Time:
Thursday, January 31, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2019-01-31T16:00:00
2019-01-31T17:00:00
Dragons orbiting the Earth and more experiences from a career in spacecraft engineering
Event Information:
Stephanie Geoffrion will share her career path as a spacecraft systems engineer for three different aerospace companies, including SpaceX. Stephanie’s role at SpaceX was multi-faceted, with her acting as a liaison between SpaceX and the engineers at NASA who work on the International Space Station. She ensured that all aspects of the interface between SpaceX's Dragon space capsule and the space station were understood, implemented and verified before flight. She was also involved in the development of the next version of Dragon, which will soon carry astronauts to the space station.
Event Location:
Hennings 201
Event Time:
Thursday, January 31, 2019 | 2:00 pm - 3:00 pm
Event Location:
HENN 318
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2019-01-31T14:00:00
2019-01-31T15:00:00
CM Seminar: Measurement and Control of Electron Dynamics Using THz Pulses
Event Information:
Phase-locked, few-cycle pulses of THz frequency light are powerful tools for both probing and driving ultrafast dynamics of low energy (meV scale) excitations in condensed matter. As an example of using THz pulses as a time-resolved probe, I discuss recent multi-THz spectroscopy experiments on the widely researched hybrid organometallic halide perovskites. These solution processable materials have been successfully applied to a variety of optoelectronic devices, most notably high efficiency photovoltaics achieving up to 22% power conversion efficiency in the lab (comparable to silicon). Their long carrier lifetimes and relative insensitivity of their electronic transport properties to the presence of impurities have been puzzling when considering their similarities to other direct band gap semiconductors like GaAs. This led to a proposal that charge carriers exist as large polarons, protected against scattering by their correlation to polar lattice vibrations. In this talk, I show ultrafast THz measurements provide direct evidence for the existence of polarons in these materials, resolving the quantum dynamics of their formation.
In addition, strong field THz pulses can now be used to control the motion of charged particles on sub-cycle time scales. Along these lines, I will discuss our recent work on sub-cycle THz field emission of femtosecond electron wave packets from metal nanotips. We show that through field-assisted tunneling directly from the metal’s Fermi level, impressive electron bunch charges up to 106/shot are emitted on a sub-cycle time scale. These electrons are subsequently accelerated in the local THz field in the vicinity of the nanotip to keV energies over 100 nm length scales. We discuss possible applications as a source for single shot ultrafast electron diffraction and as a test bed for high field physics.
Event Location:
HENN 318
Event Time:
Monday, January 28, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2019-01-28T15:00:00
2019-01-28T16:00:00
CHIME results on Fast Radio Bursts
Event Information:
Earlier this month, results from the Canadian Hydrogen Intensity Mapping Experiment (CHIME) were reported in two Nature papers. Members of UBC's CHIME team will describe the experiment and these exciting new results on Fast Radio Bursts.
Event Location:
Hennings 318
Event Time:
Thursday, January 24, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2019-01-24T16:00:00
2019-01-24T17:00:00
The ultra-light axion: a candidate for wavy dark matter
Event Information:
We discuss the proposal that dark matter is comprised of an ultra-light axion-like particle. By ultra-light we mean a mass so small that the corresponding de Broglie wavelength is macroscopic, a sizable fraction of a galaxy. We will go over the particle physics motivation for this idea, in particular a derivation of the natural cosmic abundance. We will also discuss the astrophysical implications, especially ones that might help to distinguish this dark matter candidate from more conventional cold dark matter, such as WIMPs (weakly interacting massive particles).
Event Location:
Hennings 201
Event Time:
Thursday, January 24, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2019-01-24T15:00:00
2019-01-24T16:00:00
Equity and Inclusion in PHAS Elections
Event Location:
Hennings 318
Event Time:
Thursday, January 24, 2019 | 2:00 pm - 3:00 pm
Event Location:
BRIM 311, Stewart Blusson Quantum Matter Institute, 2355 East Mall
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2019-01-24T14:00:00
2019-01-24T15:00:00
CM Seminar: CHIRAL ANOMALY AND CLASSICAL NEGATIVE MAGNETORESISTANCE OF WEYL METAL
Event Information:
We present a theory of magnetotransport phenomena related to the chiral anomaly in Weyl semimetals. We show that conductivity, thermal conductivity, thermoelectric and the sound absorption coefficients exhibit strong and anisotropic magnetic field dependences. In the presence of a magnetic field the Wiedeman-Franz law in these materials can be violated. We also discuss properties of magneto-plasmons and magneto-polaritons, whose existence is entirely determined by the chiral anomaly. Finally, we discuss the conditions of applicability of the quasi-classical description of electron transport phenomena related to the chiral anomaly.
Event Location:
BRIM 311, Stewart Blusson Quantum Matter Institute, 2355 East Mall
Event Time:
Wednesday, January 23, 2019 | 1:00 pm - 2:00 pm
Event Location:
Henn 318
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2019-01-23T13:00:00
2019-01-23T14:00:00
New Sources of Gravitational Radiation: The Black Hole Graviton Laser
Event Information:
Black holes admit quantum mechanical bound states of ultra light particles such axions or neutrinos. These states can undergo quantum transitions absorbing or emitting gravitons. Graviton trajectories, in the particle picture, in principle can correspond to gravitons that orbit the black hole arbitrarily many times before finally escaping to infinity. Quantum mechanically, such graviton trajectories correspond to graviton-black hole scattering states which exhibit an arbitrarily large time delay before they emerge at infinity. The spontaneous emission of such graviton states coupled with their subsequent stimulated emission as the graviton circles around the black hole through the lasing medium, can in principle give rise to significant amplification. The observation of intense, monochromatic beams of coherent gravitons would then be a confirmation of the existence of ultra light massive particles and shed light on the properties of black holes.
Event Location:
Henn 318
Event Time:
Monday, January 21, 2019 | 3:00 pm - 4:00 pm
Event Location:
Hennings 318
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2019-01-21T15:00:00
2019-01-21T16:00:00
Radiation-Dominated Black Hole Accretion Flows
Event Information:
At high accretion rates, the outward force of radiation pressure generated by energy released by infalling matter can exceed the inward pull of gravity. Such super-Eddington accretion flows occur in many systems, such as the inner regions of quasars and luminous AGN, ultra-luminous X-ray sources (ULXs), and tidal disruption events. Understanding such flows is important not only for interpreting the spectra and variability of these sources, but also to predict the rate of growth of black holes in the early universe, and to quantify energy and momentum feedback into the medium surrounding the black hole, a process likely to be important in galaxy formation. New results from a study of the magnetohydrodynamics of luminous accretion flows, in which radiation pressure dominates, will be presented. Our results reveal new physical effects, such as turbulent transport of radiation energy, that require extension of standard thin-disk models. We discuss the implications of our results for the astrophysics of accreting black holes.
Event Location:
Hennings 318
Event Time:
Thursday, January 17, 2019 | 4:00 pm - 5:00 pm
Event Location:
Hennings 201
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2019-01-17T16:00:00
2019-01-17T17:00:00
Ultrastrong coupling of a single artificial atom to the electromagnetic field
Event Information:
I will present our results on the observation of ultrastrong interactions between an artificial atom and a one-dimensional quantum electromagnetic field. In this new regime the atom-field interaction strength is comparable to or larger than the atomic frequency. We design a tunable coupling circuit between the atom, a flux qubit, and the electromagnetic field in a superconducting transmission line, which allows us to explore the transition from weak to ultrastrong coupling. The experiments rely on coherent measurements of scattering of microwaves by the atom. We observe a linewidth comparable to the atomic frequency, a clear signature of ultra-strong coupling. We also find that the atomic frequency is systematically smaller than the bare atomic frequency, in agreement with renormalization by the field.
In the second part of the talk I will discuss experiments in which we apply strong driving to the atom. We show that the driving amplitude can be used to change the threshold for the coherent to incoherent transition for atom dynamics, as observed spectroscopically and in agreement with theory.
Finally, I will discuss prospects for the study of the atomic time dynamics in the ultra-strong coupling regime and its implications for investigations of open system physics, quantum optics, and relativistic quantum information.
Event Location:
Hennings 201
Event Time:
Thursday, January 17, 2019 | 2:00 pm - 3:00 pm
Event Location:
311 - 2355 East Mall
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2019-01-17T14:00:00
2019-01-17T15:00:00
CM Seminar: Coherent soft X-ray scattering and imaging of electronic textures in quantum solids
Event Information:
Strongly-correlated electron systems with competing collective electronic phases are often inherently granular. The spatial organization of the electronic degrees of freedom is essential to understand the phenomenology of these complex systems, yet there are currently no probes of the charge, spin, and orbital degrees of freedom that can simultaneously afford momentum-space sensitivity and nanoscale spatial resolution.
In this talk, I will show recent resonant soft X-ray scattering and imaging studies of the spatial textures of electronic orders (charge/spin-density-waves) in cuprate high-Tcs and rare earth nickelate thin films. For the cuprates, I will present evidence of a doping-induced transition from a 'Wigner glass' to a 'Wigner crystal' state in electron-doped Nd2CuO4, that occurs around the characteristic doping of the Fermi surface reconstruction (~10%).
For thin films of rare earth nickelate NdNiO3, I will discuss scanning resonant magnetic nanodiffraction (<100 nm resolution) experiments to elucidate the spatial organization of spin-density-wave domains as a function of temperature across the Neel transition. Intriguingly, we have observed a return-point-memory effect in the spin degrees of freedom and intrinsic scale-invariant textures with power-law correlations that might be suggestive of a second-order nature of the magnetic transition in this material.
I will conclude with some perspectives and a glimpse to very recent resonant coherent diffractive imaging experiments performed at latest-generation, highly-coherent synchrotron X-ray sources to resolve the complex (amplitude/phase) density-wave order parameter down to an ultimate resolution below 30 nm (and beyond).
Event Location:
311 - 2355 East Mall