Quantum coherence is a phenomenon that plays a crucial role in various forms of matter. The thriving field of quantum information as well as unconventional approaches to use mesoscopic systems in future optoelectronic devices provide the exciting background for this set of lectures.

The lectures originate from the well-known Schladming Winter Schools and are carefully edited so as to address a broad readership ranging from the beginning graduate student up to the senior scientist wanting to keep up with or to enter newly emerging fields of research.

Although studies on synthetic dyes have been performed for more than 100 years, their detailed elucidation requires further extensive research. The discovery of novel high polymers, the necessity of supplying a whole range of shades and increasing require ments for dyestuffs of high fastness properties give rise to a permanent search for new dyes. Extensive investigations on dyes were also occasioned by various applications in the field of spectral sensitization and of staining of biological specimens. Another more recent development concerns the lasing properties of some organic dyes. Most...