Dynamics of exotic quantum magnets
Stefan Wessel, Fakher Assaad, Andreas Honecker
The goal of this project is to employ quantum Monte Carlo simulations for the study of the spin-dynamical properties of exotic phases in models of frustrated quantum magnetism, such as in supersolid and valence bond solids and in particular in quantum spin liquid phases and at deconfined quantum critical points. In order to access such spectral information, the quan- tum Monte Carlo approaches must be extended to include the high-precision measurement of imaginary-time-displaced correlation functions of appropriate operators. The imaginary-time data then must be analytically continued to the real-time frequency domain. Beyond the stan- dard maximum entropy approach, further stochastic algorithms have been proposed for this purpose. Their efficiency in the employed world-line quantum Monte Carlo algorithms, such as the stochastic series expansion, will be carefully assessed for frustrated spin models. Fur- thermore, we will analyze the spectral properties of effective quantum spin models describing, e.g., the long-ranged exchange interactions between magnetic adatoms in graphene layers, or ultracold polar molecules in optical lattices, as well as the spin-dynamical properties of quasi- crystalline magnetic systems.