Seminar announcement (March 1st and 8th): Exact multipolar moments of localized sources (Dr. Fernandez-Corbatón, KIT-Germany

Dear students and dear colleagues,

We invite you to follow a lecture organized in the framework of the Europhotonics Scholar program, that will be given by Dr. Ivan Fernandez-Corbatón, Project leader at Karlsruhe Institute of Technology, Germany.

This lecture (description below) will be divided in two seminars: Wednesday, March 1st from 10 to 12h and Wednesday, March 8st from 10 to 12h in the room A4 205, Campus Nord, UPC, Barcelona.

As usual, seminars are open and recommended to all students, as part of the academic program of the Master. We strongly recommend you to participate.

Exact multipolar moments of localized sources

The multipolar decomposition of electromagnetic sources is an important tool for the study of light-matter interactions. Examples range from nuclear and atomic physics, through nanophotonics and metamaterials, to the analysis of radiation by objects of astrophysical size. In chemistry, the dipolar and quadrupolar polarizabilities of a molecule determine most of its electromagnetic properties. In electrical engineering, the multipole decomposition is used to design and analyze the radiation from antennas. In these lectures, I will explain recent progress in the multipolar decomposition of electromagnetic sources. Namely, new exact and simpler expressions for the multipolar moments of electric current density distributions, and their extension to the multipolar moments of magnetization current density distributions. During the lectures, I will also use the expressions to analyze and clarify a recent development in the nanophotonics lecture, the toroidal multipoles, which are often said to be a third independent family of multipoles, besides the electric and magnetic ones, which brings about a third kind of material resonances.

The plan for the lectures is as follows:

Lecture 1:
* A multipolar derivation in momentum (wavector) space
* Parts of the source that do(do not) produce EM fields
* Exact multipolar expressions and their approximations

Lecture 2:
* Toroidal multipoles and other splits
* Helicity multipoles
* Electromagnetic duality symmetry
* A different kind of electromagnetic source: Spin
* Multipoles as irreducible representations
* More about Cartesian vs. spherical
* Transformations in the Poincaré group