Paul Charbonneau
Département de Physique, Université de Montréal

Abstract

A snowflake, a lichen, and a solar flare; my first is a crystal whose structure is set by molecular interactions at the nanometer scale; my second is a symbiotic biological organism of centimeter scale shaped by strong physical constraints; my third is an energy release event occurring in a magnetohydrodynamical system of scales reaching a million kilometers. What could these three systems possibly have in common ? In this talk I will discuss a physical modelling paradigm whereby such natural complex systems and phenomena emerge from a great many simple dynamical elements interacting locally with one another at scales much smaller than the global scale of the system. Complexity thus emerges from simplicity! However this cannot be viewed as a disguised form of reductionism, because here even perfect knowledge of microscopic dynamics cannot be used to predict macroscopic behaviour, as it does in statistical thermodynamics.

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Prof. Kent Moore
University of Toronto Mississauga

gwk.moore@utoronto.ca

Abstract

Professor Moore has for over 25 years taken the earth’s temperature and done in depth analysis on how and why it is changing. He has flown through winter storms in the Arctic, climbed some of our highest peaks, measured Artic sea ice and examined ice cores. He would like to share his findings and thoughts, so you can better understand the physics behind our changing climate and what it means to you.

Short bio

Professor Moore has a Ph.D. in Geophysical Fluid Dynamics from Princeton Univ. He is a Professor of Physics at the Univ. of Toronto, the Vice-Principal Research at the Univ. of Toronto Mississauga and a recent Fulbright Visiting Chair in Arctic Studies at the Univ. of Washington. Professor Moore’s research interests include: geophysical fluid dynamics, polar meteorology, observational studies of high latitude air-sea-ice interactions, physical oceanography, paleoclimatology and high-altitude physiology. Prof. Moore has published over 170 research papers in the peer-reviewed literature Among the journals that Professor Moore has published in include: Science, Nature, Nature Climate Change, the New England Journal of Medicine, the Journal of Climate, the Journal of Hydrometeorology, Geophysical Research Letters, the British Medical Journal, Progress in Oceanography, Deep Sea Research and the Quarterly Journal of the Royal Meteorological Society. Prof. Moore has played a leadership role in a number of national and international research collaborations aimed at improving our understanding of how the ocean and atmosphere exchange heat, moisture and momentum including the Canadian Atlantic Storms Program, the Beaufort and Arctic Storms Experiment, the Canadian GEWEX (Global Energy and Water Cycle Experiment) Program, the Labrador Sea Deep Ocean Convection Experiment, the Greenland Flow Distortion Experiment, the Storms of the Arctic Experiment and the Iceland-Greenland Sea Project.

 

Nir Rotenberg
University of Copenhagen

Abstract

Quantum photonics is no longer just an exploration of fundamental physical laws; we now also use quantum effects to construct devices to, for example, produce single photon sources or perform quantum measurement. That is, we are in the process of bringing the research from the lab and into the marketplace. This process, however, is in its infancy, and the type and power of the resultant devices still strongly depends on the way in which we can generate and manipulate quantum states.

In this talk, I focus on some of our recent results in observing and controlling nonlinear light-matter interactions using solid-state emitters coupled to nanophotonic waveguides. I begin by explaining the passive nonlinearities of these emitter-waveguide systems, and how these can form the basis for a photon sorter: a device that can enable a deterministic Bell-state measurement, and thus forms a key component of a long-range quantum network. I then turn to our recent efforts to actively control these quantum nonlinear interactions, and bring multicolor nonlinear optics to the single-photon level, thereby opening routes towards active quantum devices such as photon switches, routers, or even reconfigurable networks.

 

Rachel Friesen
University of Toronto

Abstract

The conversion of gas into stars is a key process driving the evolution of structures in the universe. Recent surveys of dust continuum emission of Galactic star-forming regions have revealed the ubiquity of filamentary structures within molecular clouds, raising the tantalizing possibility that the star formation efficiency is strongly dependent on how these dense filaments form and evolve. I will show how the combined analysis of gas dynamics and chemistry in star-forming regions is critical to understand filamentary mass accretion, stability, and fragmentation. Consequently, large-scale surveys of molecular lines that trace dense, star-forming gas are sorely needed. Filling this gap, I will present results from the Green Bank Ammonia Survey, a Large Program on the 100m Green Bank Telescope that has mapped the dense molecular gas of all the major star-forming molecular clouds within 500 pc. Finally, I will discuss how new and upcoming facilities will enable tests of star formation theory over the next decade from stellar cluster to protostellar disk scales.

 

King Yan Fong
University of California, Berkeley

Abstract

Scientists’ vision of building miniaturized machines atom-by-atom has inspired today’s micro- and nano-scale devices such as photonic, electronic, mechanical, and microfluidic systems, which have now become an integral part of our modern life. Nano-systems allows integration of different systems onto same platform to realize cross-functional devices. The enhanced light-matter interaction at nano-scale also allows light to couple with mechanical motion to achieve optical sensing and control with unprecedented bandwidth and sensitivity. Operation of nano-devices in quantum regime further opens up new prospects in sensing and information processing applications.

In this seminar, I will talk about three topics of nano-opto-mechanical systems in areas spanning from fundamental studies to practical applications. I will show you how heat transfer through quantum vacuum can be observed using nano-mechanical sensor [1], how the challenge of mechanical sensing in fluidic environment can be tackled [2,3], and how scaling of nano-system down to single atomic layer allows realization of new device functionality [4]. In the end, I will share with you my view of where further scaling and integration of nano-systems may lead to.

[1] K. Y. Fong, et al., Nature 576, 243 (2019).
[2] K. Y. Fong, et al., Nano Lett. 15, 6116 (2015).
[3] K. Y. Fong, et al., Nano Lett. 19, 3716 (2019).
[4] H.-K. Li*, Fong*, et al., Nat. Photon. 13, 397 (2019). *equal contribution

 

Nahee Park
University of Wisconsin-Madison

Abstract

In 1912, Austrian physicist Victor Hess discovered, with a high-altitude balloon experiment, a flux of highly energetic particles coming from outer space - for which he won the Nobel Prize. Now known as cosmic rays, these particles have been the topic of numerous studies ever since their discovery. Because of their deflection by magnetic fields and their interactions with particles and radiation in interstellar and intergalactic space, cosmic rays arriving at Earth carry little information about their sources. Instead, observations of the neutral particles, such as gamma rays and neutrinos, produced during the interactions experienced by cosmic rays have been studied in order to search for their elusive source sites. Observations of neutrinos provide a key element in these studies, as neutrinos can probe source environments that, due to their distance or obscuration, are inaccessible to gamma-ray observatories. Recently, the IceCube experiment located at the South Pole has revealed the first neutrino view of the cosmos, opening a new window to explore the sources of high-energy cosmic rays in our Universe. I will highlight the role that these high-energy neutrino observations play in the emerging discipline of multi-messenger astrophysics, focusing on the recent IceCube neutrino alert from a flaring blazar, TXS 0506+056. I will also discuss what we expect to learn in the future with the next-generation neutrino observatory, IceCube-Gen2, and summarize how these observations will allow us to explore fundamental physics, including searches for decaying dark matter throughout the Universe.

 

Alexander Tait
NIST: National Institute of Standards and Technology

Abstract

At low-temperature, silicon can be made to emit light, and superconducting wires can detect single photons. When integrated with silicon photonic waveguides, this combination of sources and detectors forms the basis of an emerging platform for cryogenic silicon photonics. A new photonic integrated circuit platform could potentially impact current approaches to quantum measurement, communication, and computing. The extent of these potentials depends on further development of on-chip silicon light sources. There are two frontiers: high-power sources for nonlinear optics, and very low-power (single-photon) sources for quantum optics.

Silicon photonics has opened possibilities for new concepts in optical information science - this is also true at room temperature. Neuromorphic silicon photonics has pushed the bounds of machine learning performance. As with any revolutionary computing technology, neuromorphic photonics could have unforeseen and fascinating other applications, perhaps most dramatically in autonomous analysis and control of ultrafast phenomena.

This talk will summarize recent progress in neuromorphic silicon photonics and touch on some current research frontiers. I will give an introduction to cryogenic silicon optoelectronics and describe how these physics can connect to information processing. Special attention will be given to current progress and future directions in cryogenic all-silicon light sources.

 

Ziqing Hong
Northwestern University

Abstract

Dark matter is a hypothetical form of matter that, if it exists, may account for more than a quarter of the energy density of our universe. Despite the variety of astrophysical evidence pointing to its existence, the direct interaction of dark matter in a terrestrial detector is yet to be observed. The Super Cryogenic Dark Matter Search (SuperCDMS) experiment tries to observe a dark matter signal in silicon and germanium detectors operated around 50 miliKelvin. In this talk, I will discuss the status of the next generation SuperCDMS experiment, the recent results with an eV-resolution gram-scale prototype detector, and the future plan with this technology.

 

Dr. Shawn Westerdale
Princeton University

Abstract

Dark matter comprises 27% of the energy density of the universe -- about 5 times more than baryonic matter. Despite this abundance, its nature remains a complete mystery. While several theories predict different dark matter candidates, no experimental evidence to date can confirm any of them. Many experimental efforts are currently underway, aiming to directly detect some of the most promising candidates — a challenge akin to finding a needle in a haystack. To accomplish this, large detectors can be built deep underground, where backgrounds are greatly reduced. In this colloquium, I will review techniques used to search for dark matter, focusing on the DarkSide-50 and DEAP-3600 liquid argon-based detectors. I will discuss significant advances that have been made in reducing backgrounds for these dark matter searches and in improving liquid argon detector technology, paving the way for a future set of detectors to probe low- and high-mass candidates. 

Dr. Westerdale is a candidate for the tenure-track faculty position in Particle Astrophysics.  Faculty are encouraged to meet with Dr. Westerdale during his 2 days of visits.  Students and postdocs are welcome to join for a catered lunch immediately following the colloquium in Stirling 201.

 

Dr. Laurie Barge
Research Scientist in Astrobiology at the NASA Jet Propulsion Laboratory

Abstract

To search for biology on other worlds, it is important to have working definitions of what constitutes “life” and “non-life”. However, the distinction between biotic and abiotic is often unclear, since we are still learning about the limits of life, and also because abiotic systems can become highly complex when devoid of biological influence. Although Earth provides a variety of examples of what biology can look like, examples of the critical steps between abiotic and biotic systems are lacking because the prevalence of life on our planet has contaminated / erased its record of prebiotic conditions. However, prebiotic chemistry may still be a current or formerly active process on other worlds with detected chemical gradients and organics, such as Enceladus, Ceres, or Mars. I will discuss how astrobiologists approach the search for life on other planets, and will describe some of the difficulties in distinguishing living and non-living systems. In particular I will share some of our lab work on simulating gradients in hydrothermal vents that could support life or its origin, and prebiotic chemistry experiments that aim to bridge the gap between geochemistry and the emergence of biochemistry.

Bio

Dr. Laurie Barge is a Research Scientist in Astrobiology at the NASA Jet Propulsion Laboratory. She co-leads the JPL Origins and Habitability Laboratory which studies the origin of life and how life can be detected on other planets, and she is the Investigation Scientist for the HiRISE instrument on NASA’s Mars Reconnaissance Orbiter (MRO). Dr. Barge’s research interests include the emergence of life on Earth, and organic chemistry on Mars and ocean worlds such as Jupiter’s moon Europa and Saturn’s moon Enceladus. She is also interested in hydrothermal vents as planetary analogs, and is the science lead for an underwater laser divebot that will be deployed to a vent in the Pacific in 2020. Dr. Barge received her Bachelor’s degree (2004) in Astronomy and Astrophysics from Villanova University, and her Ph.D. (2009) in Geological Sciences from the University of Southern California. After graduate school she was a Caltech postdoc and then NASA Astrobiology Institute postdoctoral fellow. For her astrobiology research Barge has received the JPL Lew Allen Award, the NASA Early Career Public Achievement Medal, and the Presidential Early Career Award for Scientists and Engineers.