Events at Physics |
Events on Thursday, November 7th, 2013
- R. G. Herb Condensed Matter Seminar
- Ultracold atoms in synthetic gauge fields: Novel phases and dynamics
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Arun Paramekanti, University of Toronto
- Abstract: Experimental developments in the field of ultracold atomic gases
have enabled the creation of artificial Lorentz forces and spin-orbit coupling. The combination of such "synthetic gauge fields" and strong correlations in an optical lattice is shown
to lead to novel phases including Mott insulators which support loop current orders and magnetic skyrmion crystals. These bosonic chiral Mott insulators are analogous to vector chiral phases of frustrated magnets. We show that studying quantum quench
dynamics yields a particularly transparent route to imaging such current orders, enabling the detection of bulk equilibrium currents as well as topological chiral edge currents. Similar
ideas are also shown to be applicable to orbital states of such ultracold atoms, leading to chiral orbital Bose liquid states. Such complex orbital order can be uncovered using quenches
which lead to orbital dynamics, analogous to NMR pulse experiments that probe spin dynamics.
- Astronomy Colloquium
- Massive Star Formation Through the Universe
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Jonathan Tan, University of Florida
- Abstract: Massive stars have played a dominant role in shaping our universe since its earliest times, but there is no consensus on the mechanism by which they form. I review the physical processes thought to be important in massive star formation, concentrating on a particular theoretical model, Turbulent Core Accretion. This assumes the initial conditions are massive, turbulent, magnetized cloud cores of gas and dust that are reasonably close to virial equilibrium. We test this via theoretical simulations of the physics and chemistry of the interstellar medium and observational searches for these cores. We next consider the protostellar collapse phase as a massive star grows from the core. Various forms of feedback become important in reducing the efficiency of accretion, although it is not clear if one particular mechanism operates to set a fundamental limit on the maximum stellar mass. Again, these theoretical ideas can be tested by observations of massive stars forming in our Galaxy today. Finally, I discuss an application of massive star formation theory to the early universe: how massive were the first stars and could they have been the progenitors of supermassive black holes?
- Host: Audra Hernandez