Upcoming Seminars
Theoretical Physics Institute Seminar
Thursday, January 18, 2024
CCIS L1-029, 12:40pm-14:00pm
SPEAKER: Duncan O’Dell, McMaster University
HOST: Lindsay LeBlanc
* Talk starts at 12:50, pizza will be served at 12:40.
For more information about this and upcoming talks see: https://www.tpi-ualberta.ca/tpi-seminar.html
The Abraham-Minkowski controversy: an ultracold atom perspective
Over 100 years ago Max Abraham and Hermann Minkowski proposed rival theoretical expressions for the momentum of light in a medium. Since then a large number of theoretical and experimental studies have been conducted which have variously supported one or the other theory. The subject remains controversial to this day, but the advent of ultracold atoms allows for simple and clean measurements that may lead to greater clarity. I will discuss this subject from the perspective of ultracold atoms and point out some unexpected connections to seemingly different physics such as the He-McKellar-Wilkens phase (the geometric phase acquired by an electric dipole moving in a magnetic field).
Department of Physics Colloquium
Friday, January 19, 2024
CCIS 1-430, 3:00 pm
SPEAKER: Duncan O’Dell, McMaster University
HOST: Lindsay LeBlanc
* Coffee and doughnuts will be available after the talk.
Quantum Catastrophes
Caustics are singularities arising from the natural focusing of waves. Examples include rainbows, the bright lines on the bottom of swimming pools, gravitational lensing, freak waves at sea, tidal bores, and event horizons. At large scales all these phenomena lead to characteristic singular patterns where the amplitude diverges and that are described by catastrophe theory. However, zooming down to short scales one finds that the singularities are smoothed by universal interference patterns that obey a remarkable set of scaling relations.
My group has been extending these ideas to quantum fields. The big question we are trying to answer is whether there are classical wave singularities that are not resolved by ordinary wave interference but that are instead regulated by second quantization? I will take you through some examples we have studied in the context of Bose-Einstein condensates including analogue black holes.
Past Seminars
Department of Physics Colloquium
Friday, October 20, 2023
CCIS 1-430, 3:00 pm
SPEAKER: Shiwei Zhang, Flatiron Institute
HOST: Frank Marsiglio
* Doughnuts and coffee available at 3:00 pm. Talk begins at 3:10 pm.
More is different: advancing quantum physics through computation
A central theme in modern physics and chemistry is to understand quantum effects in materials. An incredibly rich set of phenomena arise through the interplay between the structures/topology and particle interaction. Predicting and harnessing such effects offers many opportunities for scientific breakthroughs, which would dramatically advance applications in areas ranging from renewable energy to drug design. The task is daunting, because of the intrinsic challenges in solving the many-body Schrodinger equation. Recently, significant progress has been made with computational approaches, through algorithmic advances, community benchmarks, and the use of complementary methods in a multi-messenger manner. I will introduce some of these developments, using a linear chain of hydrogen atoms as an illustration, and discuss the prospect for systematic, predictive computations in more realistic quantum materials.
Special Seminar: Quantum Science and Technology
Thursday, October 12, 2023
CCIS L1-047, 2:00 pm
SPEAKER: Professor Nir Rotenberg, Department of Physics, Queen’s University – Quantum Nanophotonics Lab
* Coffee will be served
Linear and nonlinear photonic quantum circuits
Self-assembled quantum dots in nanophotonic structures are a wonderful platform for the exploration of fundamental physics and for quantum photonic technologies. Fundamentally, they allow for the controlled exploration of few-body effects and few-photon nonlinearities, while from a technical perspective they act as on-demand sources of single or entangled photons, all because of the high quality of both these emitters and the structures into which they are embedded. Recently, at Queen’s University, we have begun exploring other ways in which these properties could be used to realize quantum technologies, focusing on quantum photonic circuits. In this talk, I will discuss these efforts, covering what is possible if the circuits are fully linear or if nonlinearities are available, and highlighting roles that quantum dots may play.
Department of Physics Colloquium
Friday, October 13, 2023
CCIS 1-430, 3:00 pm
SPEAKER: Professor Nir Rotenberg, Department of Physics, Queen’s University
HOST: Lindsay LeBlanc
* Doughnuts and coffee available at 3:00 pm. Talk begins at 3:10 pm.
Quantum nanophotonics: from large dreams to small dots
In the midst of the second quantum revolution, when devices based on quantum mechanics begin to enter the marketplace, photonics plays a special role. After all, light-based technologies are the only way to transmit quantum information already at the millimetre scales. In this talk I will outline some of the (many) challenges facing researchers as they try to make photonic quantum technologies a reality, focusing on the quantum internet as an example. I will then discuss our platform of choice, namely semiconductor quantum dots as a way of overcoming some of these challenges. I will introduce the properties of these artificial atoms, and cover several recent experiments that demonstrate the powerful ways in which they can control light at the quantum scales, linking these results to emerging technologies where possible.
Special Seminar: Quantum Science and Technology
Monday, October 2, 2023
CCIS L1-047, 2:00 pm
Kai Shinbrough, University of Illinois, Urbana-Champaign
High-speed, high-efficiency, low-noise photonic quantum memory in neutral barium vapor
Photonic quantum memory is a critical enabling technology for quantum photonic computation, networking, and sensing. A chief advantage of the photonic platform is the speed of quantum gates; here, we review the state of the art for photonic quantum memories in the high-speed, broad-bandwidth regime, before describing our experimental demonstration of a simultaneously high-speed, high-efficiency, and low noise quantum memory in neutral atomic barium vapor. By harnessing controllable collisional dephasing as a new resource for atomic-ensemble quantum memories, we demonstrate record performance in all three metrics. The ultra-low noise performance of our memory combined with its ultrabroad bandwidth allows for full reconstruction of retrieved photon amplitude and phase through spectral interferometry. We discuss the merits of this work as well as the future work needed for practical, scalable distribution of photonic quantum memories in quantum applications.