For most of the last century, condensed matter physics has been
dominated by band theory and Landau's symmetry breaking theory. In the
last twenty years, however, there has been the emergence of a new
paradigm associated with fractionalization, topological order, emergent
gauge bosons and fermions, and string condensation. These new physical
concepts are so fundamental that they may even influence our
understanding of the origin of light and electrons in the universe. This
book is a pedagogical and systematic introduction to the new concepts
and quantum field theoretical methods in condensed matter physics. It
discusses many basic notions in theoretical physics, which underlie
physical phenomena in nature, including a notion that unifies light and
electrons. Topics covered are dissipative quantum systems, boson
condensation, symmetry breaking and gapless excitations, phase
transitions, Fermi liquids, spin density wave states, Fermi and
fractional statistics, quantum Hall effects,
topological/quantum order, spin liquid and string condensation. Methods
discussed include the path integral, Green's functions, mean-field
theory, effective theory, renormalization group, bosonization in one-
and higher dimensions, non-linear sigma-model, quantum gauge theory,
dualities, slave-boson theory, and exactly soluble models beyond
one-dimension. This book is aimed at bringing students to the frontiers
of research in condensed matter physics.