Events at Physics |
Events on Thursday, November 8th, 2018
- R. G. Herb Condensed Matter Seminar
- Interaction-induced time symmetry breaking in periodically driven oscillators
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Mark Dykman, Michigan State University
- Abstract: Quantum dynamics of a periodically driven system is described in terms of the Floquet states. Generally, if the system is in a Floquet state, its dynamical variables oscillate with the period of the driving. Recently much interest have attracted systems where this discrete time-translation symmetry is broken, the “time crystal” effect. Nonlinear oscillators, including nanomechanical systems and modes in electromagnetic cavities, provide a natural platform for studying this effect. I will discuss the classical and quantum phase transitions to the broken-symmetry state in systems of coupled oscillators. Time permitting, and for completeness, I will also show time-symmetry breaking in the simplest quantum system, a qubit.
- Host: Coppersmith
- Cosmology Journal Club
- Time: 12:00 pm - 1:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details: 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 Then and Now
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall, Coffee and cookies 3:30 PM. Talk Begins at 3:45 PM
- Speaker: Nia Imara, CfA Harvard
- Abstract: Stars are of fundamental importance to astronomy, and how they form and shape their environments influence everything from exoplanet studies to cosmology. Stars form in heavily obscured molecular clouds, and understanding the initial conditions of star formation persists as one of the leading challenges of contemporary astrophysics. A major challenge is the wide range of physical scales involved: from the large-scale galactic environment, to molecular clouds, to the high-density filaments and cores most directly associated with the birth of stars, and all the way down to the physics of dust, atoms and molecules. I will discuss ways to overcome these challenges, focusing on the birth of molecular clouds from the atomic interstellar medium, the role of high-density substructure in the formation of stars, and the properties of molecular clouds in dwarf galaxies. I will also explore some cosmological implications of stardust, proposing theoretical models for dust in high-redshift galaxies and in the intergalactic medium.
- Host: Professor Eric Wilcots