This book is intended to provide a clear and unified introduction to the physics of matter at low temperatures, and to do so at a level accessible to researchers new to the field and to graduate and senior undergraduate students. Rapid scientific progress made over the last seven years in a number of specific areas-for example, high-Tc superconductivity and the quantum Hall effect-has inevitably rendered our earlier Matter at Low Temperatures somewhat out of date. We have therefore taken the opportunity to revise and amend the text in its entirety and, at the same time, to furnish it with what we believe to be a more apt title, emphasizing that it is with the physics of low temperatures that we are particularly concerned. Like its predecessor, Low-Temperature Physics is devoted to the fascinating and diverse phenomena that occur under conditions of extreme cold, many of which have no analogue at all in the everyday world at room temperature.