Events

Final PhD Oral Examination

Icicles are harmless and picturesque winter phenomena, familiar to anyone who lives in Canada.  The shape of an icicle emerges from a subtle feedback between ice formation, which is controlled by the release of latent heat, and the flow of water over the evolving shape.  The water flow, in turn, determines how the heat flows.  The air around the icicle is also flowing, and all forms of heat transfer are active in the air.  Ideal icicles are predicted to have a universal "platonic" shape, independent of growing conditions.

The new Swiss X-ray Free Electron Laser (SwissFEL) facility at PSI delivers fsec photon pulses of coherent x-rays in the wavelength range 0.1 to 7 nm, with extremely high peak brightness. The Aramis SwissFEL branch, dedicated for hard X-ray, is in user operation with two end-stations since 2018.

Departmental Doctoral Oral Examination

Abstract:
Multiple sclerosis (MS) is a pathologically complex, autoimmune disease that results in demyelination and neurodegeneration following an inflammatory-mediated event cascade. Magnetic resonance imaging (MRI) has been essential to study MS and is now a cornerstone of MS diagnosis and clinical decision making. However, typical clinical MRIs fail to capture the complexity of the disease, because they lack specificity to myelin and other pathological mechanisms influencing myelin health in MS.

Departmental Doctoral Oral Examination

A galaxy cluster can be likened to a city of galaxies. As such we can ask questions such as how does city living affect galaxies? How do they behave differently to galaxies that are located outside of clusters and what are the physical causes of these differences? I will present the search for distant galaxy clusters as one route to answering these questions. By observing the most distant clusters known we may catch galaxies in the act of accreting onto forming clusters and witness the physics of quenching and morphological transformation in action.

Ice sheet simulations have become much more sophisticated over the last decade in their ability to capture small spatial detail and reproduce actual observed ice sheet behaviour. That does not mean that the underlying models are correct. Here we look "under the hood": the purpose of this talk is to present a survey of the physics in ice sheet models and its implications for the dynamics of ice sheets.

Abstract: A quantum emitter (QE) is a physical system that can be used to encode a quantum state via some internal degree of freedom (e.g. exciton, electron spin, valley) and is coupled to light via a dipolar transition that enables the conversion of that quantum state into the state of a photon and vice versa.

In this talk, I start by reviewing the known ways of increasing the entropy both in classical and in quantum systems, with emphasis given to recent developments (2016-19). I then relate them to black hole physics to show which ones and to which extent they apply to the Bekenstein-Hawking entropy.

Collisions with asteroids and comets used to be the stuff of science fiction.  However, starting with the Apollo missions' revelations about our Moon, it has gradually dawned on the scientific world that collisions between objects from microscopic to planetary scales dominated nearly every aspect of our planetary system's birth and its later evolution.  Long after the birth of our planet, a rare asteroid impact initiated the extinction of the dinosaurs.  As recently as Feb.

Complex oxide materials exhibit a wide range of electronic and magnetic behavior in bulk and thin films. With advances in oxide thin film deposition techniques, we are now able to realize atomically precise thin films, heterostructures and interfaces of these complex oxide materials that open up a new phase space for materials discovery. The stabilization of unusual ground states in such atomically precise complex oxide materials has led to discoveries of novel spin and topological phenomena.

Recently, van der Waals heterostructures have emerged as a very powerful platform for designer quantum materials with many fascinating properties that are not possessed by the constituent monolayers achieving novel device functionality.  In terms of designer vdW hetero-bilayers, the interlayer interaction is the controlling parameter determ

The CFHT Large Area U-band Deep Survey (CLAUDS) uses ~70 nights of dedicated dark-time imaging (plus significant additional archival data) to map a representative 18.6 square degrees of the Universe to a median depth of U = 27.1 AB (5σ).  These are the deepest U-band images ever assembled over this large an area. 

The partial award of the 2019 Nobel Prize in Physics for the discovery of exoplanets culminates four remarkable decades of search and development. While astrometry proved fruitless, stellar radial acceleration measurements of high precision revealed reflex motions induced by planetary companions. The UBC group was the first to demonstrate the power of imposed wavelength fiducials in 1979. This encouraged others to join the search – everyone was looking for solar system analogues.

The Hubbard model, first formulated by physicist John Hubbard in the 1960s, is a simple theoretical model of interacting quantum particles in a lattice. The model is thought to capture the essential physics of high-temperature superconductors, magnetic insulators, and other complex emergent quantum many-body ground states.