Liberating Exotic Slaves
  The introduction of confined, ``slave'' fields is frequently useful as a formal device in models of condensed matter physics; it becomes a conceptual necessity for describing possible phases of matter where the slaves are liberated. Here I discuss some aspects of the fractional quantum Hall effect from this point of view, emphasizing analogies with phenomena in other areas of physics, particularly to the Meissner and Higgs mechanisms, and to confinement-deconfinement transitions. In this application, and in some recent attempts to model the normal state of copper oxide superconductors, it is important to employ slave anyon fields. 
Frank Wilczek