Calculation of nonlinear susceptibility in magnetic systems

Coherent nonlinear optical spectroscopy has been a successful tool to probe interactions between excitations in NMR and semiconductor experiments. Recent advances of optical experiments in the terahertz range allows the realization of similar measurements for localized magnetic systems. Anticipating this, we are calculating nonlinear magnetic susceptibilities for well known models, such as the transverse field Ising model, and Kitaev honeycomb model. The information about the magnetic excitations can then be used as a probe to experimentally identify complex, yet elusive magnetic ground states, such as quantum spin liquids.