Specific problems that require non-equilibrium quantum field theoretic techniques for their solution include such diverse examples as topological transitions and electroweak baryogenesis, dynamics of the quark-gluon plasma and disoriented chiral condensates, effective field theories and the real-time renormalization group, and thermalization and reheating in the early universe. In addition there are applications of these methods in condensed matter physics to areas such as dynamics of phase transitions and transport of nonlinear coherent structures.
The main focus of our research group has been on the development of field theory and numerical methods for attacking time evolution problems in quantum field theory such as the back-reaction of quantum fields on classical fields as well as the dynamics of non-equilibrium phase transitions. One set of problems is related to experimental programs planned for RHIC and Fermi-lab: The processes we are studying are the production of unusual muon pairs from a time evolving quark gluon plasma produced following a relativistic heavy ion collision and the production of Centauro events (large regions with no neutral pions) from disoriented chiral condensates produced in the non-equilibrium chiral phase transition expected during the time evolution of the plasma. A second set of problems is related to fundamental issues in field theoretic dynamical systems such as the quantum-to-classical transition, the dynamics of second order phase transitions and of nonlinear coherent structures, and the thermalization of quantum fields in initial value problems. A final set of problems connects with the fields of cavity QED and atomic optics both of which have become excellent testing grounds for fundamental ideas in non-equilibrium quantum dynamics. We are providing theoretical support for experiments being carried out at Caltech and at the University of Texas, Austin.
The study of non-equilibrium field systems poses tremendous numerical challenges. Computational difficulties such as multiple length and time scales with very large dynamic range, nonlocal kernels, inclusion of fluctuations, and extreme storage requirements are typically encountered. Because of these barriers, real progress has been possible only with the advent of massively parallel computing platforms, such as the T3E now at NERSC. Looking to the near future, non-equilibrium field theory codes will require Teraflop performance as well as memory requirements in the low TBytes.