Physics Colloquium, Fall 2019

Thursdays 4:00 p.m., Room 104 Physics
Refreshments served at 3:40 p.m.


Colloquium organizer:
A.T. Le
(Link to main colloquium page)

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Title: "Modern software development for academics"

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Title:

After Rolla: A 2001 Graduate’s Perspective

 

Abstract:

This talk will cover a range of concepts centered within ultracold atomic physics. In particular it will cover the topics of molecule formation from ultracold atoms, localization of atoms in a disordered potential, and using atoms within inertial sensors and clocks. This will cover work in which I participated after my undergraduate days at Rolla.   After graduating from UMR in 2001, I attended graduate school at the University of Colorado/JILA, studying atomic physics under a Nobel Laureate and other distinguished physicists. At JILA, I helped build and use an apparatus to study controlled molecule formation from ultracold gases of atoms. After earning a PhD in 2008, I moved to the University of Illinois to help complete an apparatus which we used to study and characterize how ultra-low energy atoms localize in a disordered potential. In 2011 I accepted a job at AOSense where I helped build and design sensors utilizing ultracold atoms for use in inertial sensors and clocks.  

 

 

Dr. Navarrete will give two shorter presentations:

The role of classical uncertainties on the coherence properties of collisions processes

 Abstract: The awareness of the relevance of the projectile’s beam coherence effects in ion-atom and ion-molecule collisions has motivated an extensive study on this subject in the recent years. The traditional way to compute the fully differential cross section (FDCS) of a reaction describes the incoming beam of projectiles as a purely coherent quantum system, i.e. a plane-wave. Nevertheless, this assumption seems not justified enough when we look at this postulate under the light of the density matrix theory. We will describe how the time propagation of an incoherent mixture of an ensemble of massive particles, described by identical wave packets located at different positions upon a much larger region of dimension D, can eventually develop coherence at a given distance L, and its implications for scattering theory. Furthermore we will show results of this concepts applied to specific experimental results.

 

Multi-channel contributions to High Harmonic Generation in solids

Abstract: Unlike High-harmonic generation in solids (HHG) from gaseous atoms for which there is a great consensus and vast knowledge of its characteristics,  the main features of HHG in solids are still under discussion, which has been fueled by its recent experimental discovery. We will show a detailed analysis of the intra- and interband dynamics by an adiabatic basis-set approach within the whole BZ and how they can be easily understood by means of a simple model which allows for analytical approximations of the contributions of each separate crystal momentum channel. Furthermore, we also compare the HHG spectra for a two-band calculation and the features which emerge in a many-band calculation when we consider  the integration of the spectra over the entire BZ with contributions from the band center (Γ point) alone.

 

Finding black holes that should not exist with LIGO

Abstract: The direct measurement of gravitational waves is a powerful tool for surveying the population of black holes across the universe. From LIGO, we have already found the heaviest black holes that can be formed from stars. Recent pictures have also confirmed the super-massive black holes at the centers of the galaxy. However, there exists no evidence to date of black holes that are 100-100,000x heavier than our Sun, hinting at a fundamental mass-gap in our universe. In this talk, I will provide an overview of LIGO's search for tracing these elusive black holes and the implications it holds for the next 20 years of gravitational-wave astronomy.

 

The Hobby-Eberly Telescope Dark Energy Experiment

 Abstract:

The Hobby-Eberly Telescope Dark Energy Experiment (HETDEX) will produce the largest galaxy map of the early universe, with the goal of measuring the universe expansion rate at early times. Combining this early expansion rate with the many late-time measurements will produce unique and important leverage on the understanding of dark energy. HETDEX involves building the largest astronomical spectrograph ever, the largest survey undertaken on the biggest telescopes, and uses the leading resources of the Texas Advanced Computing Center. We recently had our first data release and I'll present the initial results and survey predictions. We are at design specification for our ability to measure the expansion rate to better than 1% accuracy.

 

 

Title: Workflow in Phenomenological High Energy Physics

Abstract:
A typical workflow is presented for phenomenological high energy physics, which serves as the bridge between particle theory and collider experiments. The core of a phenomenological study is usually a Monte Carlo simulation program, or event generator, of a collider experiment. Based on a given perturbative quantum field theory, the event generator calculates observables that can be compared to experimental data. Also presented are scattering-amplitude-based kinematic discriminant and its application in phenomenological studies, as well as a few recent results.

Dr. Shun Saito and Dr. Thomas Vojta will present a lecture about the 2019 Nobel Prize in Physics, which was awarded "for contributions to our understanding of the evolution of the universe and Earth's place in the cosmos" with one half to James Peebles "for theoretical discoveries in physical cosmology", the other half jointly to Michel Mayor and Didier Queloz "for the discovery of an exoplanet orbiting a solar-type star."
The lecture is intended for a general audience and will be suitable for interested community members. 

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