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DY: Fachverband Dynamik und Statistische Physik

DY 15: ISPS Intersectional Poster Session

DY 15.24: Poster

Tuesday, March 15, 2011, 18:00–20:00, P1

Projection operator approach to spin diffusion in the anisotropic Heisenberg chain at high temperatures — •Robin Steinigeweg¹ and Roman Schnalle² — ¹Institut für theoretische Physik, Technische Universität Braunschweig, D-38106 Braunschweig — ²Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld

Spin transport in the anisotropic Heisenberg chain is typically investigated theoretically w.r.t. the finiteness of transport coefficients only. Assuming their finiteness at high temperatures, we develop a concrete quantitative picture of the diffusion constant/(dc-)conductivity as a function of both the anisotropy parameter Δ and the spin quantum number s, going beyond the most commonly considered case s=1/2. Using this picture, we enable the comparison of finite transport coefficients from complementary theoretical methods on a quantitative level, having more significance than the finiteness alone. Our method is essentially based on an application of the time-convolutionless projection operator technique to current autocorrelations. This technique, although being a perturbation theory in Δ, is found to be applicable, even if Δ is not small. This finding supports the applicability to a wider class of strongly interacting many-particle quantum systems.