  Multi-component quantum systems in strong interaction with their environment
are receiving increasing attention due to their importance in a variety of
contexts, ranging from solid state quantum information processing to the
quantum dynamics of bio-molecular aggregates. Unfortunately, these systems are
difficult to simulate as the system-bath interactions cannot be treated
perturbatively and standard approaches are invalid or inefficient. Here we
combine the time dependent density matrix renormalization group methods with
techniques from the theory of orthogonal polynomials to provide an efficient
method for simulating open quantum systems, including spin-boson models and
their generalisations to multi-component systems.
