ABSTRACT
Bose-Einstein Condensates are often considered as the fifth state of matter. There is an enormous beauty in their physics and there is a lot to be learned from them, as they are the ideal systems to observe quantum phenomena in a macroscopic level. Atomic condensates have attracted a huge interest after their first observation in 1995 by Cornell [15] and Ketterle [16] and, although they are extremely difficult to achieve, many groups worldwide carry out fundamental research on them. The main difficulty that is inherent to atomic condensates is the extremely low temperatures that are needed (on the order of nanokelvin) because of the large mass of atoms. Things would be much simpler if the condensing bosonic particles where less heavy. Along this line, solid state systems have been proposed as candidates for condensation and extended efforts have been done for the demonstration of condensation of magnons [26], excitons [27] and more recently polaritons [21]-[25]. In this chapter, the basics of condensation will be presented along with the basics of microcavity polaritons.
