Quantum quenches and competing orders

Abstract We study the non-equlibrium dynamics of an electronic model of competition between an unconventional charge density wave (a bond density wave) and d-wave superconductivity. In a time-dependent HartreeFock+BCS approximation, the dynamics reduces to the equations of motion of operators realizing the generators of SU(4) at each pair of momenta, (k, k), in the Brillouin zone. We also study the nonequilibrium dynamics of a quantum generalization of a O(6) non-linear sigma model of competing orders in the underdoped cuprates (Hayward et al., Science 343, 1336 (2014)). We obtain results, in the large N limit of a O(N) model, on the time-dependence of correlation functions following a pulse disturbance. We compare our numerical studies with recent picosecond optical experiments. We find that, generically, the oscillatory responses in our models share various qualitative features with the experiments.