Events at Physics
Events During the Week of April 30th through May 7th, 2017
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Advances in Stellarator Optimization
- Time: 12:00 pm
- Place: 2317 Engineering Hall
- Speaker: Dr. David Gates, Princeton Plasma Physics Laboratory, USA
- BAUTZ LECTURE
- Physics Of The Stochastic Excitation Of Stellar Modes
- Time: 12:00 pm
- Place: 4421 Sterling Hall
- Speaker: Peter Goldreich, CALTECH
Internal properties of stars with convective envelopes are determined by analyzing the frequencies of their acoustic modes. After a brief introduction to observational techniques, I will describe the emission, absorption, and scattering of sound inside a star and how the waves ultimately escape through its photosphere. Then I will demonstrate how these processes account for some remarkable regularities revealed by observations of solar modes across 3 orders of magnitude in angular degree.
- Host: UW Astronomy Department
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
Please 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 Amol Upadhye (email@example.com).
- Host: Josh Berger
- Council Meeting
- Time: 12:00 pm
- Place: 2314 Chamberlin hall
- Chaos & Complex Systems Seminar
- Year-end celebration
- Time: 12:05 pm
- Place: 4274 Chamberlin (refreshments will be served)
- Abstract: Following the tradition of recent years in which we had a delightful discussion of where we have come and where we might go with the seminars, this last seminar of the semester will be devoted to a continuation of that discussion without any formal speaker. We will also discuss what we want to do during our informal weekly lunches on the Memorial Union Terrace which begin on May 9th. This celebration will include expanded refreshments, to which your own culinary contribution is welcome.
- Host: Clint Sprott
- Department Meeting
- Time: 12:15 pm
- Place: 5310 Chamberlin hall
- Speaker: Albrecht Karle
- R. G. Herb Condensed Matter Seminar
- Coherent defects in diamond
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Nathalie de Leon, Princeton
- Abstract: Engineering coherent systems is a central goal of quantum science and quantum information processing. Point defects in diamond known as color centers are a promising physical platform. As atom-like systems, they can exhibit excellent spin coherence and can be manipulated with light. As solid-state defects, they can be produced at high densities and incorporated into scalable devices. Diamond is a uniquely excellent host: it has a large band gap, can be synthesized with sub-ppb impurity concentrations, and can be isotopically purified to eliminate magnetic noise from nuclear spins. Specifically, the nitrogen vacancy (NV) center has been used to has been used to demonstrate basic building blocks of quantum networks and quantum computers, and has been demonstrated to be a highly sensitive, non-invasive magnetic probe capable of resolving the magnetic field of a single electron spin with nanometer spatial resolution. However, realizing the full potential of these systems requires the ability to both understand and manipulate diamond as a material. I will present two recent results that demonstrate how carefully tailoring the diamond host can dramatically improve the performance of color centers for various applications.
First, currently-known color centers either exhibit long spin coherence times or efficient, coherent optical transitions, but not both. We have developed new methods to control the diamond Fermi level in order to stabilize a new color center, the neutral charge state of the silicon vacancy (SiV) center, which exhibits both the excellent optical properties of the negatively charged SiV center and the long spin coherence times of the NV center, making it a promising candidate for applications as a single atom quantum memory for long distance quantum communication.
Second, color centers placed close to the diamond surface can have strong interactions with molecules and materials external to the diamond. However, uncontrolled surface termination and contamination can degrade the color center properties and give rise to noise that obscures the signal of interest. I will describe our recent efforts to stabilize shallow NV centers within 5 nm of the surface using new surface processing and termination techniques. These highly coherent, shallow NV centers will provide a platform for sensing and imaging down to the scale of single atoms.
- Host: Brar
- Astronomy Colloquium
- The IllustrisTNG Simulations: Elemental Evolution in Cosmological Simulations
- Time: 3:30 pm
- Place: 4421 Sterling Hall, Cookies and Coffee at 3:30 PM, Talk at 3:45 PM
- Speaker: Jill Naiman, CfA Boston
- Abstract: I will give an overview of some of the new features of the IllustrisTNG models - a set of gravitational, hydrodynamical, MHD cosmological simulations aimed at resolving from the formation of galaxy clusters down to the structures of Milky Way dwarf galaxies. A brief overview of AREPO, the code used in these simulations, and updates from its first cosmological implementation in the Illustris simulations will be presented. I will conclude with some preliminary results on the distribution of elements in our simulations, in particular, the distribution of Europium in Milky Way sized galaxies.
- Host: Prof Elena Donghia
- Physics Department Colloquium
- Simulating the Ionosphere, one electron at a time
- Time: 3:30 pm
- Place: 2103 Chamberlin hall
- Speaker: Meers Oppenheim, Boston University, Astronomy Department
- Abstract: All planetary atmospheres have a region where solar radiation ionizes the air, creating an ionosphere; a plasma extending from the upper atmosphere to the space environment. For the Earth, the ionosphere extends from 80 km above the ground, where neutrals outnumber ions by over 8 orders of magnitude, to around 1000 km, where ions and neutrals have similar numbers. This region absorbs the majority of EUV and X-rays from the Sun. Energetic particles from the magnetosphere, the solar wind, and the cosmos slam into it. Billions of meteors deposit tons of materials in it, daily. From below, winds and turbulence in the Earth’s atmosphere push it around. All these interactions make the ionosphere complex and interesting. NASA and the space community need accurate models of the ionosphere since the International Space Station and most of our spacecraft exist within it, and can experience harmful radiation and electric charging. The ionosphere was first discovered because of its impact on radio communication and its interference with Earth to Space communications and GPS remain critical issues. This talk will present the basics of ionospheric plasma physics, present a method of simulating ionospheric plasmas, the Particle-in_Cell (PIC) method. It will then show how we used this method to study a number of turbulent processes in the ionosphere and what we have learned from these studies.
- Host: Jan Egedal