Recent experimental developments in quantum optics have opened
up possibilities to create strongly correlated states of matter with sizable
electromagnetic or photonic components. Enabled by strong atom-photon
coupling on the single-quantum level, for example in cavity QED and with
Rydberg atoms, it is now possible to study the statistical, and generically
far-from-equilibrium, physics of photons in new regimes far beyond
what is know from the laser theory developed in the 1970's. Here, I will
survey our first attempts to classify such phases of photonic matter into
universality classes including glasses, superradiant Fermi gases, and
attractive quantum liquids.
In the second part, I will consider electronic materials in which
frustration and interactions are so strong that, collective excitations
made out of electronic spins behave as emergent photons, and compute
new observable signatures thereof.
Further information: http://www.thp.uni-koeln.de/~strack/