For quantum spin systems in equilibrium, the dynamic structure factor (DSF) is among the most feature-packed experimental observables. However, from a theory perspective it is often hard to simulate in an unbiased and accurate way, especially for frustrated and high-dimensional models at intermediate temperature. To address this challenge, we compute the DSF from a dynamic extension of the high-temperature expansion to frequency moments. We focus on nearest-neighbor Heisenberg models with spin lengths S=1/2 and 1. We provide comprehensive benchmarks and consider a variety of frustrated two- and three-dimensional antiferromagnets as applications. In particular we shed new light on the anomalous intermediate temperature regime of the S=1/2 triangular lattice model and reproduce the DSF measured recently for the S=1 pyrochlore material NaCaNi_{2}F_{7}. An open-source numerical implementation for arbitrary lattice geometries is also provided.
The dynamical dimer structure factor is an observable probing spin-singlet excitations of quantum magnets distinct from those commonly studied by the spin structure factor. We report the dimer response for the extended spin-
1/2 antiferromagnetic Heisenberg model on the triangular lattice using large-scale GPU-accelerated matrix-product-state simulations. We investigate the ordered phases with
120∘ coplanar, collinear stripe, and tetrahedral spin order, as well as candidate quantum spin-liquid (QSL) regimes, comprising an expected gapless
U(1) Dirac QSL and a chiral QSL at finite spin-scalar-chirality coupling. In the ordered phases, we find low-energy modes below the onset of the two-magnon continuum illustrating avoided quasiparticle decay. Within the candidate gapless QSL, we observe absolute dispersion minima at momenta of half the Brillouin zone corners,
X≡K/2, in agreement with field-theory predictions that singlet monopole excitations of the
U(1) Dirac spin liquid become gapless at these points. Thus, the high-resolution dynamical dimer response provides support for a
U(1) Dirac QSL with singlet monopole excitations.
Abstract Programmable quantum simulators based on neutral atom arrays today offer powerful platforms for studying strongly correlated phases of quantum matter. Here, we employ the projective symmetry group framework to describe the symmetry fractionalization patterns in a topologically ordered
Z2 Z 2 quantum spin liquid (QSL) synthesized in such a Rydberg array on the ruby lattice. By systematically comparing the static structure factors of all possible mean-field Ansätze against density-matrix renormalization group calculations, we identify a promising candidate for the precise
Z2 Z 2 QSL realized microscopically. We also present detailed analyses of the dynamical structure factors as a reference for future experiments and showcase how these spin correlations can differentiate between varied QSL Ansätze .