Quantum theory is one of the most important intellectual developments in the early twentieth century. The confluence of mathematics and quantum physics emerged arguably from Von Neumann's seminal work on the spectral theory of linear operators. This volume arose from a two-month workshop held at the Institute for Mathematical Sciences at the National University of Singapore in July–September 2008 on mathematical physics, focusing specifically on operator algebras in quantum theory.This volume is essentially written for graduate students and young researchers so that they can acquire a gentle introduction to the application of operator algebras to quantum information sciences, chaotic and many-body problems. Several lecture notes delivered during the workshop by experts in the field were specially commissioned for this volume.