Events at Physics |
Events on Thursday, October 2nd, 2008
- R. G. Herb Condensed Matter Seminar
- Quantum transport and its classical limit
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Piet Brouwer, Cornell University
- Abstract: The interference of multiply scattered quantum mechanical matter waves causes small but noticeable corrections to the electrical conduction of a metal at low temperatures. What is the fate of quantum interference corrections in the limit that the wavelength of the electrons becomes small in comparison to all other relevant length scales? This limit is a "classical limit" similar to the transition from wave optics to ray optics that occurs when the typical size of optical elements becomes much larger than the wavelength of light. Surprisingly, the answer is not at all trivial: Whereas the interference correction to the ensemble-averaged conductance (weak localization) disappears in this classical limit, the quantum interference contribution to the sample-specific conductance fluctuations survives.
The "classical limit" is relevant for conductors in which the electron motion is ballistic and the only source of scattering is specular reflection off sample boundaries or artificial macroscopic scattering sites. In this talk, I'll outline the basic structure of a theory of quantum transport in ballistic conductors, as well as possible experimental signatures that distinguish ballistic conductors and their disordered counterparts.
- Host: Vavilov
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- LSST, the most complete survey of the sky: How tools of particle physics can serve in astronomy
- Time: 4:00 pm
- Place: 4274 Chamberlin
- Speaker: Michael Prouza, FZU Prague, Czech Republic
- Abstract: For a few decades it is clear that astronomy and particle physics share a number of interesting topics. The Large Synoptic Survey Telescope (LSST) is one of the newest proofs that these two significantly different communities can also effectively cooperate within one project. Construction of the unique 8.4-meter LSST telescope started earlier this year. The telescope will be equipped with a huge 3.2 Gigapixel camera and will have a field of view of 10 square degrees. During single 15-second exposures it will capture stars up to 25th magnitude, and the whole accessible sky will be covered every three nights. During 10 years of operation, the LSST will create a "movie of the deep space" - each spot on the sky will be imaged at least 300 times. After its completion in 2014, the LSST will be the most advanced surface tool for the mapping of dark energy and dark matter, and the most sensitive instrument for detection and identification of any transient sources. Thus, the LSST will e.g. collect an unprecedented number of supernovae and will identify the trajectories of most of the so-called Earth Threatening Asteroids. In my talk I will discuss the current status, the technical challenges, and the potential scientific impacts of the LSST project.
- Host: Stefan Westerhoff