Events at Physics |
Events During the Week of November 3rd through November 9th, 2019
Monday, November 4th, 2019
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Future of Nuclear Power in a Carbon-constrained World
- Time: 12:05 pm - 12:55 pm
- Place: 2241 Chamberlin Hall
- Speaker: Michael Corradini, UW-Madison
- Host: John Sarff
Tuesday, November 5th, 2019
- Chaos & Complex Systems Seminar
- A Tiny Earth, global crises
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Speaker: Sarah Miller, Wisconsin Institute for Discovery
- Abstract: Tiny Earth is a network of instructors and students focused on crowdsourcing antibiotic discovery from soil. The network aims to (1) inspire students to pursue careers in science through original research conducted in introductory courses with the potential for global impact, and (2) address two worldwide threats -- the diminishing supply of effective antibiotics and the soil erosion crisis. Each year, nearly 10,000 students implement Tiny Earth across 44 states, Puerto Rico, Washington DC, and 19 countries. In this seminar, learn about the importance of these threats and the studentsourcing approach.
- Host: Clint Sprott
Wednesday, November 6th, 2019
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- The MICROBOONE Neutrino Experiment at Fermilab.
- Time: 2:30 pm - 3:30 pm
- Place: Chamberlin 4274
- Speaker: Wouter Van De Pontseele
- Abstract: MicroBooNE is a liquid argon time projection chamber in the Booster Neutrino Beam at Fermilab. The technology provides high-resolution imaging of neutrino interactions leading to low-threshold event reconstruction with full angular coverage. As such, this is an ideal place to probe neutrino-argon interactions in the hundreds-of MeV to few-GeV energy range. This talk presents a start-to-end overview demonstrating the physics capabilities of the detector. I will talk about cosmic ray measurement and characterisation, our dominant background. Furthermore, I will describe the flavour-agnostic neutrino pre-selection, based on the combination of the charge collected by the TPC and the optical information form the PMT system. An overview of recent measurements of neutrino interactions in MicroBooNE, including inclusive charged-current interactions, will be given. I will conclude summarising the ongoing efforts towards our first low-energy-excess results
- Host: Francis Halzen
- Theory Seminar (High Energy/Cosmology)
- Interiors for AdS Black Holes
- Time: 4:00 pm - 5:00 pm
- Place: 5280 Chamberlin Hall
- Speaker: Sagar Lokhande, UIUC
- Abstract: I will start with a pedagogical review of the modern formulation of Black Hole Information Paradox. I will explain how this reformulation casts doubt on the smoothness of the event horizon and on the existence of a local effective field theory near the horizon. I will make brief comments on two prominent approaches to the resolution of the Paradox. Then, I will specialize to black holes in AdS spacetime and discuss the construction of interior operators for typical black holes. I will propose specific thought experiments involving out-of-time-order correlators (OTOC) that provide evidence for the existence of such operators. The AdS/CFT correspondence, a celebrated duality derived from string theory, plays a crucial role in this investigation. Finally, if time permits, I will discuss some work-in-progress to construct the interior operators for more general, non-typical AdS black holes using the theory of operator algebras.
- Host: Nicholas Orlofsky
Thursday, November 7th, 2019
- R. G. Herb Condensed Matter Seminar
- Atom-based Silicon Devices for Quantum Technologies
- Time: 11:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Dr. Rick Silver, NIST
- Abstract: NIST is using atomically precise fabrication to develop electronic devices for use in quantum information processing, quantum materials research and quantum sensing. We are using hydrogen-based scanning probe lithography to enable deterministic placement of individual dopant atoms with atomically aligned contacts and gates to fabricate single electron transistors, single atom transistors, few-donor/quantum dot devices for spin manipulation, and arrayed few-donor devices for quantum materials and analog quantum simulation research. We have developed robust lithography, device relocation, and contact processes that enable routine electrical measurement of atomically precise devices with an emphasis on atom-scale control of the device geometry. In addition to our fabrication technology, I will discuss the characterization of atomic-scale tunnel junctions and single electron transistors that demonstrate stable coulomb blockade oscillations with charge offset drift of 0.007e per day. I will present measurements of tunnel coupling in single electron transistors and donor-dot devices where the tunnel gap is controlled at the atomic scale as well as measurements and modeling of single and few atom transistors that display large electron addition energies, consistent with single or few dopant atom charging energies. We have recently extended our STM-patterning to fabricate coupled arrays of few atom clusters having multiple donors per dot, including a functional 3×3 quantum dot array device. Using the Si(100)2x1 surface reconstruction as an atomic ruler, we design the separation between nearest neighbor dots to be in the regime from weakly coupled to strongly coupled. We are analyzing the tunnel couplings and energy spectra in individual dots versus across an array of coupled dots to explore the rich physics of dot-arrays. Bio: Richard Silver is a physicist leading the atom-based silicon quantum electronics effort at NIST. His research focusses on fabrication, design, and measurement of atom-based Si structures that rely on single or few atoms, precisely placed within an epitaxial silicon environment for solid state quantum computing and analog quantum simulation. He received his bachelors in physics from the University of California at Berkeley and his PhD in physics from University of Texas at Austin. He is an adjunct professor with the physics department at the University of Maryland, College Park.
- Host: Eriksson
- Cosmology Journal Club
- Time: 12:00 pm - 1:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Ross Cawthon (cawthon@wisc.edu) and Santanu Das (sdas33@wisc.edu). - Astronomy Colloquium
- Star Formation and Nuclear Activity: Dwarf Galaxies to Ultraluminous Infrared Galaxies
- Time: 3:30 pm - 5:00 am
- Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM, Talk begins 3:45 PM
- Speaker: George Privon, University of Florida
- Abstract: The stellar mass of star forming galaxies is thought to increase in a quasi-steady state, where the rate depends on the gas fraction and star formation efficiency, which evolve with redshift. Galaxy mergers can lead to more rapid growth while active galactic nuclei have been argued to play an important role in halting star formation. These processes are tied together through the multi-phase interstellar medium. I will discuss programs exploring so-called "dense gas" tracers and the behavior of starbursts in merging dwarf galaxies. I will also describe a theoretical/modeling program to use galaxy formation simulations as "ground truth" for interpreting observational tracers of the ISM. This use of multiwavelength tracers and hydrodynamic simulations probes galaxy evolution along axes of nuclear activity, redshift, gas fraction, and metallicity. From these studies I will show new results on identification of heavily obscured AGN and intriguing differences in how mergers affect the evolution of high gas fraction galaxies.
- Host: Professor Emeritus Jay Gallagher
Friday, November 8th, 2019
- Theory Seminar (High Energy/Cosmology)
- Black Holes to Algebraic Curves: Consequences of the Weak Gravity Conjecture
- Time: 11:00 am - 12:30 pm
- Place: Chamberlin 5280
- Speaker: Tom Rudelius, Institute for Advanced Study, Princeton
- Abstract: The Weak Gravity Conjecture holds that in any consistent theory of quantum gravity, gravity must be the weakest force. This simple proposition has surprisingly nontrivial physical consequences, which in the case of supersymmetric string/M-theory compactifications lead to nontrivial geometric consequences for Calabi-Yau manifolds. In this talk we will describe these conjectured geometric consequences in detail and show how they are realized in concrete examples, deriving new results about 5d supersymmetric black holes in the process.
- Host: Gary Shiu
- Physics Department Colloquium
- Introduction to Quantum Error Correction: Schrödinger meets Maxwell’s Demon
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall
- Speaker: Steven Girvin, Yale
- Abstract: A ‘second quantum revolution’ is underway based on our new understanding of how information can be stored and manipulated using quantum hardware. Even more remarkable than the concept of quantum computation is the concept of quantum error correction. We know that measurement ‘back action’ disturbs a quantum state when we observe it. Nevertheless, it is possible to store an unknown quantum state and, if it develops errors due to imperfect hardware, we can measure and correct such errors to recover the original unknown state. Crucially, we must be able to do this without ever learning anything about that unknown state. This talk will present an elementary introduction to the basic theoretical concepts underlying quantum error correction for discrete systems (qubits) as well as for continuous-variable systems (harmonic oscillators).
- Host: Alex Levchenko