Felicia Magpantay
Department of Mathematics and Statistics at Queen’s

Abstract

Much of the theory and applications of delay differential equations (DDEs) focuses on constant and time-dependent time delays. How- ever, many delays in physical (e.g. action-at-a-distance electrodynam- ics), biological (e.g. structured population models) and engineering (e.g. automatic position control) systems naturally vary with the state of the system and lead to state-dependent delay differential equations (SDDEs). In this talk I will present some background on the theory and applications of DDEs and SDDEs, and sketch ideas behind how to show the stability of solutions to SDDEs using Lyapunov-Razumikhin methods. Similar techniques can be used to derive bounds on periodic solutions. This is joint work with A.R. Humphries (McGill University).

Prof. Gilles Gerbier
Queen's University

Abstract

"23% (6.6 million) of Canadians aged 15 and older reported that most days were ‘quite a bit’ or ‘extremely stressful’ (2013, Stats Canada)."   

Students are expected to be good learners, and be "successful", while professors, teachers are expected to be the best teachers to attract new students, to be "successful" as well while leading innovative research projects. Meeting expectations is felt as source of stress, of tensions. All suffer the stress of having to be on time, with all duties perfectly done, of succeeding on all exams, research projects etc..  I will discuss  details of these drivers, their mechanics, the role of time and a way to balance their impact  through attention and presence. Everyone is welcome to participate.

Prof. David G. Cooke
Department of Physics, McGill University

Abstract

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. We 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. The nanotip provides a local field enhancement of the intense THz fields to an astounding 10’s of GV/m near the tip apex. 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 quasi-statically within the half-cycle of the THz pulse to keV energies. I discuss implications for this new ultrafast electron source for both time-resolved electron scattering experiments and as a test bed for high field physics. 

Finally, I discuss a new platform for dynamic THz photonics based on a light-addressable silicon-filled waveguide. The platform allows virtually any metal-dielectric photonic structure to be created within the 2D waveguide, both statically and dynamically on time scales that are faster than the pulse transit time and even the THz carrier wave. I will discuss several functionalities enabled by this platform, including arbitrary pulse shaping and the trapping light.

Dr. Laura Fissel
National Radio Astronomy Observatory

Abstract

The conversion of gas into stars underlies much of modern astrophysics, from planet formation to the chemical evolution of our universe.  A key outstanding question in star formation research is whether magnetic fields significantly contribute to the low star formation efficiency we observe. In this talk, I will discuss what we have learned about the role played by magnetic fields in star formation, with a particular focus on results from the BLASTPol balloon-borne sub-mm polarimeter. BLASTPol operates 38.5 km above the Earth’s surface (above 99.5% of the atmosphere), resulting in much better sensitivity compared to ground-based polarimeters. By statistically comparing detailed BLASTPol-inferred magnetic field maps of a massive molecular gas cloud with simulations, we find that magnetic fields play an important role in the formation of both low- and high-density gas sub-structures.  Our next-generation balloon-borne polarimeter, BLAST-TNG, is scheduled for a first Antarctic flight in December 2019. With BLAST-TNG we will apply these same analysis techniques to a larger sample of clouds with 5x better resolution, and quantitatively determine the extent to which magnetic fields affect star formation efficiency. Finally, I will discuss prospects for building an even more powerful balloon-borne sub-mm observatory that can access most of the sky as part of NASA’s new Super-Pressure balloon program.

Dr. Coral Wheeler
Caltech

Abstract

The currently favored cosmological paradigm has been widely successful in predicting the counts, clustering, colors, morphologies, and evolution of galaxies on large scales. However, fundamental questions remain unanswered within the model, with perhaps the most glaring being the fundamental nature of dark matter. Clues to these unknowns may come from the several challenges that have arisen to the model in recent years, most of which occur at the smallest scales — those of dwarf galaxies (Mstar < 10^9 Msun). These low mass galaxies are the most dark matter dominated objects in the Universe, and so it is now the smallest scales of galaxy formation that have the best chance of revealing truths about our overall cosmological framework. I will introduce a suite of extremely high-resolution cosmological simulations of dwarf galaxies that allow us to probe smaller physical scales than previously possible in cosmological simulations, and argue that the study of the counts and kinematics of low-mass galaxies can inform our understanding of galaxy formation, and the nature of dark matter itself.

Shohini Ghose
Professor, Physics and Computer Science at
Wilfred Laurier University
Director, Centre for Women in Science (WinS)

Abstract

Women have made important contributions in all areas of science and technology. Yet the proportion of women in many areas of science and engineering, including physics, remains low.  What can we do to build an inclusive science community? I'll discuss the data on the current status of women in science. Where do we stand today and what can we improve? You decide.

Chiara Mingarelli
Flatiron Institute, Center for Computational Astrophysics

Abstract

Galaxy mergers are a standard aspect of galaxy formation and evolution, and most (likely all) large galaxies contain supermassive black holes. As part of the merging process, the supermassive black holes should in-spiral together and eventually merge, generating a background of gravitational radiation in the nanohertz regime.  An array of precisely timed pulsars spread across the sky can form a galactic-scale gravitational wave detector in this band. I describe the current efforts to develop and extend the pulsar timing array concept, together with recent limits which have emerged from international efforts to constrain astrophysical phenomena at the heart of supermassive black hole mergers. 

Dr. Shohini Ghose
Professor, Physics and Computer Science, Wilfred Laurier University
Director, Centre for Women in Science (WinS)

Abstract

From the structure of atoms, to the composition of stars, to teleportation, quantum physics has led to amazing discoveries over the past century. Understanding the microscopic world of atoms and photons has also led to modern technologies like lasers and computers that have transformed our lives. Yet the quantum world remains a mysterious place full of strange phenomena such as entanglement and quantum uncertainty. This is the story of my voyage into this weird and wonderful invisible world, and the surprising lessons I learned about physics and about being a physicist.

Bio

As a girl, Dr. Shohini Ghose was inspired by Rakesh Sharma, the first Indian to go to space and wanted to become an explorer like him. She hasn’t made it to space yet, but she did become an explorer of the quantum world. She is a theoretical physicist who examines how the laws of quantum physics can be harnessed to transform computing and communication. She also supports and celebrates women scientists as the Director of Laurier’s Centre for Women in Science. She loves teaching and has co-authored a bestselling astronomy textbook. Dr. Ghose is the recipient of several awards including a TED Senior Fellowship in 2018. She is a Researcher at the Perimeter Institute for Theoretical Physics, an Affiliate of the Institute for Quantum Computing, and a Fellow of the Balsillie School of International Affairs. In 2017, she was named to the Royal Society of Canada’s College of New Scholars, Artists and Scientists. Dr. Ghose is working to create a vibrant and inclusive physics community in Canada as the Vice-President of the Canadian Association of Physicists.

If you have any accessibility concerns, please contact Ms. Kyra Funk. Phone: 613-533-2707  |  Email: funkk@queensu.ca

All are welcome!

Nigel Smith
SNOLAB

Abstract

Astroparticle physics is addressing some of the most challenging questions in contemporary science including the nature of dark matter and the fundamental properties of neutrinos. Over the last fifteen years, the use of liquid argon and xenon systems in direct dark matter searches and neutrinoless double beta decay has led to substantial progress in closing out parameter space in both fields. This talk will explore the benefits of using liquid noble detectors in these areas, the current status of projects and their future plans, including major opportunities for Canadian research at the SNOLAB facility.

Andrei Klishin
University of Michigan and Harvard University

Abstract

Physical manufacturing is no longer the main part of new product manufacturing costs, surpassed by design. At the same time, the complexity of designed systems is rapidly rising, as they attempt to integrate more and more functions. Together these trends call for new perspectives on not just the outcomes of the design process, but on the process itself. Here we propose a new approach to design investigations that we term "Systems Physics", leveraging the methods of statistical physics and materials science. Drawing example problems from Naval Engineering, we use Systems Physics to pose principally new questions about design, delineate the qualitatively different regimes of problem behavior and illuminate a host of new physical phenomena that occur in design spaces. We also develop new computational methods based on tensor networks that can be readily applied to conventional statistical physics problems.