Calendar of Physics Talks Vienna
|Spin-orbit interactions of light|
|Abstract:||I will give an overview of the fine spin-orbit phenomena which appear in evolution of polarized light and optical vortex beams at subwavelength scale. These are spin and orbital Hall effects, spin-to-orbitangular momentum conversion, etc. Interference of partial waves gaining geometric-phase gradients underlies these phenomena and provides their “wave” description. At the same time, conservation and dynamics of the angular-momentum degrees of freedom of light provides a “particle” picture of the spin-orbit interactions. The spin-orbit effects appear in most of the basic optical processes (such as interference, diffraction, scattering, focusing, reflection, etc), and are of a great importance for modern nano-optics.|
|Date:|| Tue, 09.09.2014|
|Duration:|| 90 min|
|Contact:||Arno Rauschenbeutel - Philipp Schneeweiß|
|New Methods for Gauge Theories|
|Speaker:||Thomas Strobl (Lyon U.)|
|Abstract:||The established method for the construction or understanding of gauge theories consist in the gauging of a rigid symmetry group where for each
symmetry parameter one extends the original functional by one appropriate gauge field. We introduce drastically new alternatives to this:
1. Often it is sufficient to introduce a smaller number of gauge fields only; this permits to gauge some infinite-dimensional rigid symmetries
with a finite number of gauge fields.
2. The condition of a rigid symmetry can be relaxed in the sense of making it change from point to point, permitting to gauge also rigid Lie
3. There are situation where one can gauge even in the absence of a symmetry.
We attempt to keep the presentation rather elementary, assuming only some basic knowledge of differential geometry.
|Date:|| Wed, 10.09.2014|
|Duration:|| 60 min|
|Location:||SEM 136 (Freihaus, Wiedner Hauptstrasse 8-10), Institute for Theoretical Physics, Vienna University of Technology|