Past Events

Chemical Kinetics in Microdroplets

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Abstract: Over that last 10+ years there has emerged some evidence that when a reaction vessel is reduced to the micron-sized dimensions (e.g. droplets), bimolecular reactions speed up by many orders of magnitude. The mechanism(s) for rate acceleration in droplets remains unclear but has clear implications for understanding the chemistry of atmospheric aerosols. A key uncertainty in the interpretation of droplet kinetics is how to properly link reaction rates measured in beaker scale containers with those occurring in micron-sized spaces.

Nonlinear effects in magnetic systems: from nano to macro scales

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Abstract: Wave interactions are responsible for the various aspects of the behavior of different systems in nature, including processes in the oceans and atmosphere, star hydrodynamics, and even the evolution of the Universe. Spin waves (and their quanta–magnons) in magnetically ordered materials are highly nonlinear compared to, for example, phonons or photons in solids.

Waves of Topological Origin in the Fluid Earth System and Beyond

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Abstract: Symmetries and topology are central to our understanding of physical systems. Topology, for instance, explains the precise quantization of the Hall effect and the protection of surface states in topological insulators against scattering from disorder or bumps. However discrete symmetries and topology have not, until recently, contributed much to our understanding of the fluid dynamics of oceans and atmospheres.

Extreme Ultraviolet Spectroscopy of Ultrafast Excitations in Magnetic Alloys

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The next generation of logic devices may rely on very fast switching of magnetic states. In this thesis, I utilize ultrafast pulsed lasers to measure and manipulate magnetic states on their fundamental timescales: ranging from few-femtoseconds spin-transfers in Heusler alloys to magnetization reorientations in ferrimagnets which take tens of picoseconds. I utilize high harmonic generation to produce a tabletop extreme ultraviolet probe for resonant measurements.

Twisting, Binding, and Probing Matter Waves in a Rubidium Cavity-QED system

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Large ensembles of laser-cooled atoms interacting via photon-mediated interactions are powerful platforms for quantum simulation and sensing. In this work, I will present a cavity-QED system with matter waves coupled to a high-finesse cavity. In this system, we successfully generated entanglement between atomic momentum states and realized the first entangled matter-wave interferometer.

Understanding hydroxyl radical gas phase and heterogeneous reaction mechanisms

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Abstract: Reactions of the hydroxyl radical (OH) in the gas phase and at the gas-liquid interface initiate and propagate complex chemical schemes in combustion, planetary atmospheres, and the interstellar medium. In aqueous aerosols, the confinement of the reactants near the air-water interface leads to complex behavior of the particle reactive uptake with particle composition. In the gas phase, the branching ratio between the abstraction and addition mechanisms is highly dependent on the reactant’s structure and the gas temperature.

Measuring the stratosphere: what balloons are really doing

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Absract: The Earth’s stratosphere, which sits above the troposphere, is a difficult place to make measurements. The highest-flying aircraft can only reach the lowermost portion of the stratosphere, while space-based sensors orbiting well above are limited by technique. Balloons can profile in situ from the surface up to approximately 35 km. Thus, they are a critical measurement platform for investigating the stratospheric constituents and processes that play important roles in regulating Earth’s climate.

Witnessing quantum entanglement in solid state systems with neutron scattering

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Abstract: Quantum materials promise new states of matter and platforms for next-generation electronics, but in many cases no tractable theoretical models exist for their behavior. Compounding this difficulty is the fact that their key properties—quantum entanglement—have been historically very difficult to probe. In this talk I discuss recent work to use neutron spectroscopy to probe many-body entanglement between electron spins in real solid state materials.

Programmable quantum sensing using ultracold atoms in 3D optical lattices

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Abstract: The creation of a matter-wave interferometer can be achieved by loading Bose-Einstein condensed atoms into a crystal of light formed by interfering laser beams. By translating this optical lattice in a specific way, the traditional steps of interferometry can all be implemented, i.e., splitting, propagating, reflecting, and recombining the quantum wavefunction. Using this concept, we have designed and built a compact device to sense inertial signals, including accelerations, rotations, gravity, and gravity gradients.

What did we learn from black hole images?

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Abstract:

The data collected with the Event Horizon Telescope provided the first horizon-scale images of two nearby supermassive black holes. A tremendous amount of theoretical modeling and interpretation, including large simulation libraries and new analysis tools, were necessary to extract physical constraints from these images and perform quantitative tests of General Relativity, plasma physics, and black hole environments. In this talk, I will discuss: 1. the physics behind the simulations and where they succeeded and failed; 2.

Quantum computing: what is it and how far along are we?

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Abstract: Imagine if the act of looking at an object caused it to move – or imagine you had a pair of dice that always rolled doubles, but of different numbers each roll. These counterintuitive phenomena are commonplace in the realm of quantum mechanics, which describes systems that are generally very small, very cold, and/or very isolated from the rest of the world.