Fall 2022 Colloquium Schedule
Time: Tuesdays 3 pm to 4 pm. Refreshment starts at 2:45 pm
Venue: 25 Park Place Room 223
Colloquium contact: Yang-Ting Chien (email@example.com) and Viacheslav Sadykov (firstname.lastname@example.org)
Title and Abstract
|Aug 23||First Week of Semester / New Graduate Student Reception|
|Aug 30||Introductory Colloquium||Poster Presentations 1|
|Sep 6||Introductory Colloquium||Poster Presentations 2|
Luiz Santos (Emory University)
Host: Yang-Ting Chien
(Rescheduled to Spring 2023)
|Exploring new quantum orders in electronic fractals
Fractals are patterns of striking beauty that manifest in a myriad of natural phenomena. Notoriously, fractality emerges in the quantum energy spectrum of electrons in two-dimensional lattices subject to a magnetic field, where the relationship between fractal Hofstadter bands and the quantum Hall effect has revolutionized the understanding of topology in quantum physics. Hofstadter systems have recently experienced a renaissance caused by the advent of moiré superlattices realizing the long-sought regime of large magnetic fluxes in laboratory accessible magnetic fields. Motivated by these developments, I will theoretically discuss novel scenarios for electronic quantum orders that differ from quantum Hall states. In particular, I will show how the self-similar character of fractal bands can give rise to exotic quantum phase transitions and topological superconductivity driven purely from repulsive electronic interactions. These scenarios arise from topological and renormalization group methods newly developed to tackle the challenging yet rich properties of fractal bands, revealing the prospect for exciting new physics in fractal systems.
Ashwin Ashok (Georgia State University, Computer Science)
Host: Xiaochun He
|Driving Inter-disciplinary research through advancements in Communication, Sensing and Computing
In this talk, I will discuss the interdisciplinary work conducted in my lab, MORSE studio, at the intersection of communication and networking, IoT sensing and robotics, and smart mobile computing. Using these projects as baseline motivation, I will initiate an open forum for discussion on promoting and advancing interdisciplinary research, particularly at the intersection of environment, climate and technology.
Amber Straughn (James Webb Space Telescope)
Host: Misty Bentz
|A New Era of Astrophysics with NASA’s JWST
JWST – launched December 25 2021 – is poised to change the way we understand the universe, and we are already making some groundbreaking discoveries in just the first several months of operations. I will discuss the engineering milestones that made the mission possible, as well as the over-arching scientific themes/goals of the telescope: first galaxies around the time of cosmic reionization, galaxy assembly and evolution, the birth of stars & protoplanetary systems, and study of planets (both within the solar system and exoplanets). I will also discuss specific scientific programs approved for Cycle 1, as well as early results from the mission.
|Oct 4||Nick Wilding (Georgia State University, History)
Host: Yang-Ting Chien
|Seeing Double: Observing Galileo’s Observations of the Moons of Jupiter
An iconic manuscript preserved at the University of Michigan seems to depict Galileo’s earliest telescopic observations of the moons of Jupiter. Join GSU History professor Nick Wilding as he researches this and other Galileo manuscripts and discovers that things are not always as they seem.
Bernd Surrow (Temple University)
Host: Murad Sarsour
|Exploring the Structure and Dynamics of Matter in High-Energy Collider Experiments
Understanding the properties of nuclear matter and its emergence through the underlying partonic structure and dynamics of quarks and gluons requires a new experimental facility in hadronic physics known as the Electron-Ion Collider (EIC). A US-based facility capable of colliding high-energy polarized electron and ion beams at high luminosity has been envisaged for a long time and articulated as the highest priority for new construction. The EIC will address some of the most profound questions concerning the emergence of nuclear properties by precisely imaging gluons and quarks inside protons and nuclei, such as the distribution of gluons and quarks in space and momentum, their role in building the nucleon spin and the properties of gluons in nuclei at high energies. The EIC facility will be realized at Brookhaven National Laboratory, profiting from the existing Relativistic Heavy-Ion Collider (RHIC) facility, allowing to collide both polarized proton beams and heavy ion beams for more than two decades. High energy polarized p+p collisions at √ s = 200−500 GeV at RHIC provide a unique way to probe the proton spin structure and dynamics using well-established scattering processes. The production of jets and hadrons is the prime focus of gluon polarization studies. The production of W−(+) bosons at √ s = 500 GeV provides an ideal tool to study the spin-flavor structure of the proton. After a summary of final results concerning the spin structure and dynamics of quarks and gluons obtained by the STAR experiment at RHIC, the status and perspectives of a US-based ElC facility will be presented in this colloquium, including highlights of the planned physics program, the current detector design of a new EIC experiment, and anticipated next steps.
Marco Guzzi (Kennesaw State University)
Host: Yang-Ting Chien
|The Large Hadron Collider (LHC) Era: proton dynamics and new physics searches
The CERN Large Hadron Collider (LHC) is the world’s biggest and most powerful particle accelerator. At the LHC, high-energy beams of protons traveling at approximately the speed of light, collide. I will discuss the physics of the LHC and recent developments in theory and experiments. I will highlight the role of the LHC and future colliders as precision and discovery machines. I will also discuss how our current knowledge of the structure of the proton has an impact on both precision observables and searches for new physics interactions.
Shah Bahauddin (University of Colorado Boulder)
Host: Viacheslav Sadykov
|Multi-height, Multi-scale physics in the heating of Low Solar Atmosphere
The two primary mechanisms proposed for heating the solar transition region are magnetic reconnection (nanoflares) and wave energy deposition. Our previous work using the Interface Region Imaging Spectrograph showed that the small low-lying loops residing in the transition region are multi-stranded and release bursts of energy via reconnection mediated heating. Additionally, the loop dynamics reveal coexistence of multiple timescales: simulations of the observed UV emission spectra are best reproduced when impulsive heating at the loop apex is combined with intermittent repeated heating at the footpoints on a slower timescale, as expected from magneto-acoustic wave-energy deposition. Thus, signatures of both wave and nanoflares heating may be found at different locations in the same structures. Investigation of individual sources of acoustic emission in a simulated photosphere reveal that the emission is clustered at a spatial scale of several Mm, consistent with the spatial scale of the foot-points of low-lying loops. In this talk, I will discuss (1) how the recent availability of high-resolution, multi-spectral, and polarimetric imaging data from the Daniel K Inouye Solar Telescope would enable us to trace the emission and energy deposition of photospheric waves as they propagate through the chromosphere, and (2) how these waves may drive footpoint motions of the transition region loops and possibly act as the precursor for the magnetic reconnection heating in the low corona.
Andre Bastos (Vanderbilt University)
Host: Mukesh Dhamala
|Canonical cortical circuits and dynamics for cognition
To understand the neural basis of cognition, we must understand how top-down control of bottom-up sensory inputs is achieved. We have marshaled evidence for a canonical cortical control circuit that involves rhythmic interactions between different cortical layers. By performing multiple-area, multi-laminar recordings, we’ve found that local field potential (LFP) power in the gamma band (40-100 Hz) is strongest in superficial layers (layers 2/3), and LFP power in the alpha/beta band (8-30 Hz) is strongest in deep layers (layers 5/6). The gamma-band is strongly linked to bottom-up sensory processing and neuronal spiking carrying stimulus information, while the alpha/beta-band is linked to top-down processing. Deep layer alpha/beta Granger causes that in superficial layers, and is negatively coupled to gamma. These oscillations give rise to separate channels for neuronal communication: feedforward for the gamma-band, and feedback for the alpha/beta band. Attention, working memory, and prediction processing all involve modulation of gamma and alpha/beta synchronization, both within and across areas of the frontal/parietal/visual network. These rhythmic interactions breakdown during anesthesia-induced unconsciousness. Based on these observations, we hypothesize that the interplay between alpha/beta and gamma synchronization is a canonical mechanism to enable cognition and consciousness.
David Ciardi (Caltech/IPAC)
Host: Todd Henry
|Stellar Multiplicity in Exoplanet Systems
Over the past two decades, an extraordinary revolution has ensued in our understanding of planetary systems beyond our own, driven largely by the transit missions Kepler and TESS. Because the transiting missions have relatively poor spatial resolution, high resolution imaging has become standard practice in the vetting of planetary candidates as the community works towards confirmation of a planetary transit as the source of the observed signal. Our group has become one of the largest providers of such high-resolution imaging, with near-infrared adaptive optics imaging on Keck and Palomar and with optical speckle imaging on Gemini North and South. While crucial to the confirmation of the planets themselves, the high resolution imaging has enabled us to explore the characteristics of stellar multiplicity and the planets found in those systems. I will give an overview of our decade-and-half-long program, the role our program plays in the confirmation of planets, and an assessment of the stellar multiplicity and characteristics of the planets found in those systems.
Helen Caines (Yale University), Nelson Speaker
Host: Megan Connors
|Creating little Big Bangs in the lab
Quantum Chromodynamics (QCD) predicts that the phase diagram of nuclear matter has a rich structure, including that of a deconfined state of quarks and gluons at extreme temperatures and/or pressure. We have shown that we create such a state, termed the Quark-Gluon Plasma or QGP, in the fireball generated when heavy nuclei are collided at ultra-relativistic velocities. Although we call this medium the Quark Gluon Plasma that’s a misnomer, it’s actually one of Nature’s most extreme fluids. It has a specific viscosity that is smaller than that of any known substance, including that of superfluid liquid helium, and a vorticity that surpasses that of super-cell tornado cores and Jupiter’s Great Red Spot. In addition the Quark Gluon Plasma has quark and gluon degrees of freedom and an initial temperature of a trillion Kelvin, conditions that last existed only a few microseconds after the Big Bang. Understanding the properties of the QGP and locating key features, such as the predicted first order phase transition boundary and the corresponding critical point in the QCD phase diagram, will enhance our knowledge of the universe’s evolution and the structure of all visible matters.
In this talk I will first briefly explain how we have determined these incredible properties of the Quark Gluon Plasma. I will then discuss how we are experimentally probing different regions of the QCD phase diagram by varying the energy of the colliding beams and the intriguing hints of a first order phase transition that these studies have revealed.
|Nov 22||Thanksgiving Week|
Sidong Lei (Georgia State University, Physics and Astronomy)
Host: Sebastien Lepine
|Advanced Device Fabrication and Architectures Enabled by 2D Materials
2D materials combine multiple unique physical, chemical, and mechanical properties, and thus, continuously inspire new device fabrication strategies and architectures for applications in sensing, energy harvesting, consumer electronics, and many more. In this talk, I will present our recent progress in developing advanced electronic and optoelectronic devices by leveraging this uniqueness. I will introduce a 2D-based adaptive miniature image sensor architecture, which can correct optical aberrations, such as chromatic aberrations and field curvature. This feature can significantly simplify the design of the optical lens for image capturing. Along with the compact device sizes, these image sensors can be drastically downscale the size of cameras to fit in micro-robotics for medical and environmental applications. Besides, I will also discuss the lateral integration techniques for large-scale 2D device fabrication, as well as the vertical coupling and electronic transport behavior across the interfaces on stacked 2D layers. These studies will advance the 3D integration of electronic and optoelectronic devices with more compact volume, faster operation speed, and stronger functions than the current planar integration configurations. Additionally, I will introduce the advanced manufacturing techniques, newly observed mechanical properties of 2D materials, and our home-developed facilities for material processing and characterization in this talk.
|Dec 6||Final Exam Week Starts / No Colloquium|