Spin diffusion and dynamical susceptibility of Kitaev spin liquid

Quantum spin liquids (QSLs) are exotic phases of matter that exhibit disordered spins even at absolute zero temperature, yet possess stable topological order. Among various QSL models, the Kitaev model on a two-dimensional honeycomb lattice has become a paradigmatic system due to its intriguing properties, including topologically non-trivial gapless ground states and fractionalized excitations. The potential application of these fractionalized excitations in quantum computing has generated considerable interest in the field.



In this study, we elucidate the absence of spin diffusion in Kitaev QSLs at any temperature by leveraging the integrability of the Hamiltonian. Our analysis demonstrates that local magnetic perturbations induce no spin diffusion, as confirmed by numerical results. We show that this absence of diffusion is not solely due to short correlation lengths but also arises from anisotropy in correlations, both originating from conserved Z2 flux.



Furthermore, we investigate the dynamic magnetic susceptibility of different Kitaev phases and its dependence on temperature. This analysis complements recent experiments and may serve as an observable probe for the elusive topological quantum phase transition in Kitaev models.



Our findings contribute to a deeper understanding of quantum spin liquids and their potential applications in quantum computing, emphasizing the unique transport properties of these exotic quantum states.