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Apr 1 | 10:30 - 11:30am
Chengyi Luo/Thompson Group

Twisting, Binding, and Probing Matter Waves in a Rubidium Cavity-QED system -- JILA Thesis Defense
JILA X317
Abstract & Event Details

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. Without coupling the momentum states to the internal states, we also realized momentum-exchange interactions and collective XYZ models in a Bragg interferometer, which leads to one and two-axis counter-twisting dynamics with momentum states, and a collective recoil mechanism that effectively binds wave packets together to suppress Doppler dephasing.

Apr 1 | 2:30 - 3:30pm
Sinéad Ryan/KM Group

Extreme Ultraviolet Spectroscopy of Ultrafast Excitations in Magnetic Alloys -- JILA Thesis Defense
JILA X317
Abstract & Event Details

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.

Apr 3 | 4 - 5pm
Brad Marston/ Brown University

Waves of Topological Origin in the Fluid Earth System and Beyond -- Physics Department Colloquium
JILA Auditorium
Abstract & Event Details

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. In this talk I show that, as a consequence of the rotation of the Earth that breaks time reversal symmetry, equatorial Kelvin and Yanai waves emerge as topologically protected edge modes. The non-trivial topology of the bulk Poincaré
waves is revealed through their winding number in frequency - wavevector space. Bulk-interface correspondence then guarantees the existence of the two equatorial waves. I discuss our recent direct detection of the winding number in observations of Earth’s stratosphere. Thus the oceans and atmosphere of Earth naturally share basic physics with topological insulators. As equatorially trapped Kelvin waves in the Pacific ocean are an important component of El Niño Southern Oscillation, the largest climate oscillation on time scales of a few years, topology plays a surprising role in Earth’s climate system. We also predict that waves of topological origin will arise in magnetized plasmas. The waves may appear in laboratory plasma experiments, and they may also arise in the solar system and beyond.

 

Apr 5 | 4 - 5pm
Kevin Wilson / Lawrence Berkeley National Laboratory (LBNL)

Chemical Kinetics in Microdroplets -- Phys Chem/Chem Phys Seminar
JILA Auditorium
Abstract & Event Details

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. This challenge lies, in large part, in understanding the complex kinetic coupling of adsorption, desorption, and diffusion that link chemistry occurring at the surface of an aerosol or droplet with processes occurring in its interior. In this talk I will review our recent work combining novel single droplet experiments with stochastic reaction diffusion models to develop more robust understanding of reaction rates in small compartments where interfaces play a prominent role.

Apr 27 | 1 - 2am
Prof. Alysia Marino / Dept. of Physics, U. of Colorado Boulder

ZAP! Electricity & Magnetism -- CU Wizards Program
Duane Physics Room G1B30
Abstract & Event Details

May 18 | 9:30 - 10:30am
Prof. Eric Cornell / Dept. of Physics & JILA, U. of Colorado Boulder

SPEED! -- CU Wizards Program
Duane Physics Room G1B30
Abstract & Event Details

Jun 29 | 9:30 - 10:30am
Prof. Andrew Hamilton / Dept. of Astrophysical & Planetary Sciences & JILA, U. of Colorado Boulder

BLACKHOLES! -- CU Wizards Program
Fiske Planetarium
Abstract & Event Details
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