Events at Physics
Events on Thursday, May 3rd, 2012
- R. G. Herb Condensed Matter Seminar
- Non-classical noise in quantum optomechanical systems
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Aashish Clerk, McGill University
- Abstract: A key goal in the fields of quantum optomechanics and electromechanics is to measure and hopefully control truly quantum behaviour in a "large" mechanical resonator. In this talk, I will start by giving a quick introduction to these two rapidly growing fields. I will then discuss recent experimentally-motivated theoretical work which calculates the full statistics of low-frequency energy fluctuations of a driven, quantum resonator. Surprisingly, these fluctuations are highly non-classical: they are most naturally described by a quasi-probability distribution, which can be negative. Somewhat surprisingly, this effect has a close relationship to the statistics of electronic charge transfer (so-called "full counting statistics") in mesoscopic superconducting conductors. I will discuss how these effects might be measured, and how they represent a kind of non-classical behaviour similar to the violation of a Leggett-Garg inequality. While the emphasis is on phonons, our results apply equally as well to the photon fluctuations of a driven cavity.
- Host: Vavilov
- Astronomy Colloquium
- Here be dragons :The Dynamic Radio Sky
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Geoffrey Bower, University of California - Berkeley
- Abstract: Radio variability probes a wide range of astrophysical phenomena from the solar system to the early Universe including black holes, neutron stars, gravitational wave sources, and relativistic shocks from collapsing stars. Radio follow-up of events discovered at optical, X-ray, and gamma-ray wavelengths demonstrates a rich phenomenology but we lack a systematic and sensitive view of radio variability. Our efforts in recent years with the Very Large Array (VLA) and the Allen Telescope Array (ATA) have provided the beginnings of an unbiased exploration on time scales from milliseconds to decades. Powered by development of unique digital instrumentation, new algorithms, and new survey strategies, our surveys have defined the shape of next generation radio telescopes and surveys. In particular, these surveys are shaping our understanding of radio supernovae, tidal disruption events, and gravitational-wave sources. Planned surveys with newly commissioned national facilities such as the Expanded Very Large Array (EVLA), the Australian SKA Pathfinder (ASKAP), and the South African MeerKAT telescopes coupled with the development of new instrumentation will extend our reach into new parameter space.
- Host: Eric Wilcots