Quantum dynamics far from equilibrium: a case study in the spherical model

Abstract: The application of quantum Langevin equations for the study of non-equilibrium relaxations is illustrated in the exactly solved quantum spherical model. Tutorial sections on the physical background of non-markovian quantum noise, the spherical model quantum phase transition, the long-time limit of the quantum Langevin equation of the spherical model and physical ageing are followed by a brief review of the solution of the non-markovian time-dependent spherical constraint and about the consequences for quantum ageing at zero temperature, after a quantum quench.