Abstracts Physics

Nonequilibrium and nonlinear dynamics in collective spin models and implementations using quantum feedback control

by Manuel H Munoz Arias

Out-of-equilibrium dynamics generalizes the study of ground states of quantum Hamiltonians at zero temperature, to that of dynamical quasi-steady states of quantum systems far from equilibrium. In this dissertation I discuss dynamical quantum phase transitions and out-of-equilibrium phases of matter in models of collective spins with multi-body interactions. These models, based on collective degrees of freedom, allow an exact description of the thermodynamic limit via the mean-field description. In this limit, the nonequilibrium dynamics of properties of quantum states is mapped to the nonlinear dynamics of classical variables, and thus it can be analyzed using tools from the theory of classical dynamical systems. The description of the novel dynamical quantum phase transitions and out-of-equilibrium phases of matter enabled by multi-body interactions, is complemented with an experimental protocol consisting on measurement-based quantum feedback control techniques for their implementation. The work in this dissertation constitutes a first step into the investigation of out-of-equilibrium dynamics of quantum systems with multi-body interactions and their implementations using quantum control techniques.