Mark Wilson
University of Toronto

Abstract

The ability to efficiently convert low-intensity light between the visible and infrared would be an enabling technology—particularly for applications such as 3rd-generation photovoltaics, biological imaging, and sensitized silicon focal plane array detectors with cost-effective response in the short-wave infrared (SWIR; λ:1‒3µm). Accordingly, we are advancing our new approach that combines two excitonic materials—conjugated organic molecules and colloidal quantum dots—to achieve broadband, non-coherent photon up-conversion from the SWIR to the visible. 

To achieve upconversion, we synthesize lead sulfide nanocrystals that can absorb infrared photons, and fabricate devices where these excitations sensitize the spin-triplet excited state of a nearby organic semiconductor (e.g. rubrene). In the molecules, strong exchange-splitting allows the excitonic energy to be combined via triplet fusion to create visible light. To-date, in solid state devices, we have observed upconversion from light at the threshold of the SWIR (λ=1.1μm→612nm),1 and have achieved upconversion efficiencies of 7±1% with λ=808 nm excitation by using ligand engineering to optimize Dexter-mediated nanocrystal→molecule energy transfer.2

However, although colloidal quantum dots are attractive SWIR sensitizers— their optical gap can be tuned during synthesis, and their photoexcitations are functionally spin-mixed at room temperature—there is much more to be done. For instance, while transient spectroscopy shows that our SWIR upconversion approach could be maximally efficient with only 1/10th the intensity of natural sunlight1, poor exciton transport in the nanocrystal films—due in part to energetic disorder resulting from size-dispersity and quantum confinement—presently hinders light gathering and hampers low-intensity performance. Here, our recent work has uncovered that a pre-nucleation cluster intermediate has historically frustrated efforts to synthesis low-dispersity ensembles of small (⌀<4 nm) PbS nanocrystals, and showed that process additives can enable one-step growth and yield markedly narrower heterogeneous linewidths.3 Further, our recent experiments with a novel molecular dimer in solution suggest that asymmetric coupling between triplet-pair spin states can allow the overall-quintet state to play a beneficial role in the kinetic scheme of triplet fusion, ultimately lifting the expected spin-statistical efficiency limit from 25% to 66%,4 and offering a route to all-in-one free-floating upconverting fluorophores for imaging.

References

1. Wu, M.; Congreve, D. N.; Wilson, M. W. B.; Jean, J.; Geva, N.; Welborn, M.; Van Voorhis, T.; Bulović, V.; Bawendi, M. G.; Baldo, M. A. Solid-State Infrared-to-Visible Upconversion Sensitized by Colloidal Nanocrystals. Nature Photonics 2016, 10 (1), 31–34.
    
2. Nienhaus, L.; Wu, M.; Geva, N.; Shepherd, J. J.; Wilson, M. W. B.; Bulović, V.; Van Voorhis, T.; Baldo, M. A.; Bawendi, M. G. Speed Limit for Triplet-Exciton Transfer in Solid-State PbS Nanocrystal-Sensitized Photon Upconversion. ACS Nano 2017, 11 (8), 7848–7857.
    
3. Green, P. B.; Narayanan, P.; Li, Z.; Sohn, P.; Imperiale, C. J.; Wilson, M. W. B. Controlling Intermediates in the Synthesis of PbS Nanocrystals. Submitted 2020.
    
4. Imperiale, C. J.; Green, P. B.; Miller, E. G.; Damrauer, N. H.; Wilson, M. W. B. Triplet-Fusion Upconversion Using a Rigid Tetracene Homodimer. The Journal of Physical Chemistry Letters 2019, 7463–7469.

Tami Pereg-Barnea
McGill University

Abstract

The interest in topological condensed matter dates back to the early days of the quantum Hall effect in the late 80's. Back then though, the role of topology was not entirely clear and it was thought that the interesting physics of the quantum Hall effect are unique to systems where time reversal invariance is broken. The excitement therefore grew with the discover of time-reversal invariant topological insulators in 2005.  This has led to the Nobel prize of 2016, awarded to some of the field's pioneers - Kosterlitz, Thouless and Haldane.

The introduction of topology to the classification of states of matter is arguably one of the most important paradigm shifts of our time. We now understand that states of matter should be classified not only by their dimensionality and symmetries (the notions in heard to Landau's Fermi liquid theory) but also by their topological properties.

In this talk I will present a biased view of the advances in the field and the challenges ahead. I will organize the discussion in three parts: fundamental, complex and applications. The 'fundamental' part will include research done in the direction of organizing the possible phases of materials and some known examples. The 'complex' part will focus on research into topological condensed matter systems beyond the clean, equilibrium and non-interacting limits and the 'applications' part will discuss driving, manipulating and realizing topological systems and possible applications.

Matt Dobbs
McGill University Physics and CIfAR Senior Fellow

Abstract

Technology advances have opened a new era of radio observations. We are now monitoring the sky at millisecond cadence and discovering a vast catalog of new fast radio transients while simultaneously making deep maps of structure in the universe using hydrogen intensity mapping as a tracer. While these fields are still in their infancy, early results are rolling out, fuelling discovery and motivating the design for new instruments.

Cory Dean
Department of Physics, Columbia University

Abstract

Atomically thin crystals such as graphene, boron nitride and the transition metal dichalcogenides continue to attract enormous interest. Encompassing a wide range of  properties, including single-particle, topological and correlated phenomenon, these 2D materials represent  a rich class of materials in which to explore both novel physical phenomenon and new technological pursuits. By integrating these materials with one another, an exciting new opportunity has emerged in which entirely new layered heterostructures can be fabricated with emergent properties beyond those of the constituent materials. In this talk I will discuss some of our recent efforts where,  by tuning the geometry of  these heterostructures at the nanoscale, we are able to realize yet a new level of control over their electronic properties. In particular I will discuss the significant role played by the rotational alignment between adjacent layers and the approach we are taking towards manipulating this degree of freedom to dynamically tune device properties in ways that are not possible with conventional materials.

Hossam Gaber
University of Ontario Institute of Technology (UOIT)

Abstract

This talk will present research planning, design and control strategies of energy-water-transportation infrastructures to support smart cities and communities. The talk will cover resiliency and performance measures to achieve smart energy, water, and transportation infrastructures using interconnected micro energy grids and mobile microgrids with hybrid energy storage systems. The talk will demonstrate modeling, control, and optimization techniques and their applications to improve the regional and global performance of energy-water-transportation infrastructures. Integrated data centers will be discussed to support the implementation in smart cities and during emergencies.

Bio

Dr. Gabbar is a full Professor in the University of Ontario Institute of Technology (UOIT) in the Faculty of Energy Systems and Nuclear Science, and cross appointed in the Faculty of Engineering and Applied Science, where he has established both the Energy Safety and Control Lab (ESCL) and Advanced Plasma Engineering Lab. He is the recipient of the Senior Research Excellence Aware for 2016, UOIT. He is leading national and international research in the areas of smart energy grids, safety and control systems, advanced plasma systems and their applications on nuclear, clean energy and production systems. He is leading research in Canada with international recognition in energy safety and control for nuclear and energy production facilities. Dr. Gabbar obtained his B.Sc. degree in 1988 with first class of honor from the Faculty of Engineering, Alexandria University (Egypt). In 2001, he obtained his Ph.D. degree from Okayama University (Japan) in the area of Safety Engineering. From 2001 till 2004, he joined Tokyo Institute of Technology (Japan), as a research associate in the area of process systems engineering. From 2004 till 2008, he joined Okayama University (Japan) as a tenured Associate Professor, in the Division of Industrial Innovation Sciences. From 2007 till 2008, he was a Visiting Professor at the University of Toronto, in the Mechanical Engineering Department.

He has more than 220 publications, including patents, books / chapters, journal and conference papers. He been invited and participated in world-known conferences and delivered plenary talks on number of scientific events and invitations to international universities. He has supervised and hosted undergraduate, graduate, postdocs, visiting researchers and scholars from different countries including: Japan, India, Qatar, Egypt, Mexico, Malaysia, China, Brazil, Chile, UAE, and Colombia.

He is finalist for the Graduate Student Supervision Excellence award in Ontario Tech University, 2019. He participated and led several large scale national and international projects, in Japan, China, Middle East, and Canada, related to smart energy grids, intelligent control systems and safety design and operation synthesis and optimization of energy systems, micro energy grids, and integrated gas-power grids. He developed novel solutions for risk-based smart energy grid design, protection, and control and hybrid energy supply systems. He proposed new integrated energy storage system based on flywheel and battery, and applied on power substations, transportation electrification, and urban infrastructures. Dr. Hossam Gaber has scholarly research in the area of smart energy grids, and control optimization of micro grid and transportation electrification technologies, and his recent book on Smart Energy Grid Engineering was published with national and international recognition. Dr. Gaber is regularly consulted and provide technical support for advanced energy systems in China, Middle East, Japan, and Canada, and invited to give lectures in number of national and international events in the area of smart energy grids. He is leading a research team for a funded project by Chinese government to design and deploy hybrid energy storage systems. He is the founding general chair of the annual IEEE Smart Energy Grid Engineering Conference, which is held in Canada.

Avery Broderick
Perimeter Institute

Abstract

Black holes are, without question, one of the most bizarre and mysterious phenomena predicted by  Einstein’s theory of general relativity. They correspond to infinitely dense, compact regions in space and time, where gravity is so extreme that nothing, not even light, can escape from within.  And, their existence raises some of the most challenging questions about the nature of space and time. Over the past few decades, astronomers have identified numerous tantalizing observations that suggested that black holes are real. This past April, the search for confirmation changed dramatically with the publication of the first image ever taken of a black hole, rendering tangible what was previously only the purview of theory and science fiction. I will describe how these observations were made, how the images were generated, how quantitative measurements were obtained, and what they all mean for gravity and black hole astronomy. 

Prof. Howard Carmichael
University of Auckland, New Zealand

Abstract

Quantum jumps are emblematic of all things quantum. Certainly that is so in the popular mind…and more than an echo from the past, "quantum jumps" still hold a prominent place in the lexicon of physics today. What, however, is the character of these "jumps" on close inspection? Discontinuous and discrete, as in Bohr’s original conception…or perhaps a version of Schrödinger’s continuous evolution, which might be "tracked", even interrupted and turned around? This seminar re-visits the jumps of single trapped ions from the mid-1980s [1] where quantum trajectory theory favours the latter option. I present the theoretical prediction and its recent experimental verification [2]: real-time monitoring tracks the jumps of an artificial atom in a superconducting circuit—the continuous path is reconstructed and the jumps interrupted and turned around.

[1] W. Nagourney et al., Phys. Rev. Lett. 56, 2797 (1986); T. Sauter et al., Phys. Rev. Lett. 57, 1696 (1986); J. C. Bergquist et al., Phys. Rev. Lett. 57, 1699 (1986).
[2] Z. K. Minev, S. O. Mundhada, S. Shankar, P. Rheinhold, R. Gutiérrez-Jáuregui, R. J. Schoelkopf, M. Mirrahimi, H. J. Carmichael, and M. H. Devoret, “To catch and reverse a quantum jump mid-flight,”  Nature 570, 200 (2019).

www.quantamagazine.org/quantum-leaps-long-assumed-to-be-instanta...

physicsworld.com/a/to-catch-a-quantum-jump/

www.quantamagazine.org/how-quantum-trajectory-theory-lets-physic...

Sean Molesky
Princeton University

Abstract:

In this presentation, we will describe how properties of the electromagnetic scattering 𝕋 -operator can be used to set absolute ceilings for any given bounding region and material on a variety of optical processes, ranging from thermal emission, scattering and absorption for propagating waves, to near-field based phenomena like radiative emission from a dipole in the presence of a plasmonic resonance and heat transfer across a nanoscale gap. 

Unifying the two overarching strategies of prior work on electromagnetic limits---modal decomposition (quasi-normal modes, Fourier and multipole expansions) and conservation principles—these 𝕋 -operator bounds are meaningfully applicable to all length scales, show a physically plausible scaling with material quality, and in the large characteristic length limit reproduce familiar ray-optics results. 

We will then discuss the usefulness of 𝕋 -operator bounds in the context of computationally driven "inverse-design" (optimization) algorithms and provide specific examples of structures that nearly reach the performance limit set by our analysis.

Eve Lee
McGill University

Abstract:

From gas-poor Earths to gas-rich Jupiters, planets come in a variety of sizes. I will describe the physics behind the diversity of exoplanets---how the core and gas assembly processes give rise to the observed distribution of radii and orbital periods. Basic astrophysical considerations of gas dynamical friction, gravitational scattering, collisional mergers, and gas accretion by cooling inform us that planets smaller than Neptune likely emerged in situ, in the late stages of disk evolution. Larger planets on the other hand must have nucleated from massive cores that assemble in the early stages of disk evolution. I will show how the theory of star-disk-planet interaction can describe the observed planet occurrence rate as it varies across orbital periods, planet radii, and stellar metallicities.

Prof. Valery Radchenko
Research Scientist at TRIUMF
Adjunct professor at UBC Chemistry

Abstract

The use of radionuclides has become more and more common in the diagnosis and therapy of cancer. Targeted radionuclide diagnostics and therapy based on the combination of appropriate radionuclides with selective delivery systems (e.g. antibody, peptides etc.) maximizes precision of the imaging as well as minimizes the damage of healthy tissues during therapy. Furthermore, based on imaging (tumor sizes and locations), appropriate therapeutic radionuclides emitting alpha, beta- particles or auger electrons can be utilized. After production, in most cases, medical radionuclides need to be isolated from the target material and preconditioned for further radiopharmaceutical application.

Appropriate bifunctional chelator systems should be in place to effectively attach some of the radionuclides (e.g. radiometals) to biomolecules.

Several examples of production strategies of medical radionuclides with relation to TRIUMF facilities will be presented.