Mott Insulators, Spin Liquids and Quantum Disordered Superconductivity

These introductory lecture notes describe recent results on novel Mott insulating phases which are "descendents" of superconductors - obtained by "quantum disordering". After a brief overview of quantum magnetism, attention is focussed on the spin-liquid phase of the two-leg Hubbard ladder and the "nodal liquid" - a descendent of the $d_{x^2-y^2}$ superconductor. These notes, which will appear in a future Les Houches publication, are self-contained and an effort has been made to keep them accessible.
Comment: RevTex, 28 pages with 7 figures, Signifigant changes in Sections VIII VIII and IX