9319264 Tsui Technical abstract: The fractional quantum Hall effect (FQHE) and related physics of strong correlations in two dimensions will be studied in advanced GaAs/A1xGa1-xAs heterostructures at low temperatures and high magnetic fields. The research has three objectives: (1) To use novel sample structures to study tunneling into the FQHE liquid and to investigate boiling of the liquid; (2) To investigate the role of disorder in determining the nature of the reentrant insulator around the 1/5 FQHE liquid and the physics governing the transition between them; and (3) To search for the Josephson-like currents in the double layer FQHE state. Non-technical abstract: It has been possible to realize two dimensional electron systems in advanced materials of semiconductor single-crystal thin film structures of different chemical compositions. The physical properties of these electrons differ fundamentally from the ordinary three-dimensional charge carriers in bulk semiconductors. Specifically, the charge carriers condense, in the presence of a high magnetic field, into an incompressible electron liquid. It is proposed to carry out a series of experiments which seek to determine under what conditions does this new liquid boil, when and if it freezes, does it freeze into a two dimensional electron crystal or some other form of electron matter. ***