Dynamics of fractionalization in quantum spin liquids
Physical review B: Condensed matter and materials physics American Physical Society 92:11 (2015) ARTN 115127
Abstract:
We present the theory of dynamical spin response for the Kitaev honeycomb model, obtaining exact results for the structure factor (SF) in gapped and gapless, Abelian and non-Abelian quantum spin-liquid (QSL) phases. We also describe the advances in methodology necessary to compute these results. The structure factor shows signatures of spin fractionalization into emergent quasiparticles: Majorana fermions and fluxes of Z2 gauge field. In addition to a broad continuum from spin fractionalization, we find sharp (δ-function) features in the response. These arise in two distinct ways: from excited states containing only (static) fluxes and no (mobile) fermions, and from excited states in which fermions are bound to fluxes. The SF is markedly different in Abelian and non-Abelian QSLs, and bound fermion-flux composites appear only in the non-Abelian phase.Passive correction of quantum logical errors in a driven, dissipative system: A blueprint for an analog quantum code fabric
Physical Review A American Physical Society (APS) 91:6 (2015) 062324
Magnetism in rare-earth quasicrystals: RKKY interactions and ordering
EPL (Europhysics Letters) IOP Publishing 110:1 (2015) 17002
Understanding the damage of polymer matrix composites by integrating chemical, morphological and mechanical properties
Proceedings of the American Society for Composites - 30th Technical Conference, ACS 2015 (2015)
Abstract:
Detailed physical and mechanical characterization of the matrix as well as the interphases of polymer matrix composites can lead to a more complete understanding of failure mechanisms in polymer matrix composite (PMC). This study illustrates mechanical damage of polymers in both the bulk, as well as around the interphase region through integrated computation & experimentation approach. We have developed a quantum mechanics-molecular dynamics framework, which has enabled the prediction of bond scission under load, creation of intermittent free radicals, and exploration of the potential energy surface for possible secondary reactions immediately following bond scission. In parallel, we have conducted experiments with epoxy systems with varying molecular weight and cross-linker density at different load conditions to benchmark the simulation findings of the chemical species present on fracture surfaces of the polymer. In order to evaluate experimentally molecular level effects of mechanical load in epoxy-systems, detail characterizations were conducted combing spectroscopy (X-ray photoelectron spectroscopy, FT-Infrared spectroscopy), microscopy (HRTEM, AFM-IR, SEM), X-ray diffraction (SAXS) and mechanical testing (3-point bending). Similarly, the nanoscopic nature of interphases of PMCs in terms of topography, chemical mapping/bonding, fractography, and modulus are also studied in order to find a bridge between nanoscopic, microscopic and macroscopic mechanical properties.Doping a topological quantum spin liquid: Slow holes in the Kitaev honeycomb model
Physical Review B American Physical Society (APS) 90:3 (2014) 035145