Berlin 2005 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 11: Correlated Electrons - Spin Systems and Itinerant Magnets: Theory
TT 11.7: Vortrag
Samstag, 5. März 2005, 10:15–10:30, TU H2053
Control of Local Relaxation Behavior in Closed Bipartite Quantum Systems — •Harry Schmidt and Günter Mahler — Institut für Theoretische Physik 1, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart
We investigate the decoherence of a spin 1/2 weakly coupled to an environment of many spins 1/2 with and without coupling. The total system is closed, its state is pure and evolves under Schrödinger dynamics. Nevertheless, the considered spin reaches a quasi-stationary equilibrium state.
We find that this state depends strongly on the coupling to the environment on the one hand and on the coupling within the environmental spins on the other. In particular we focus on spin star geometries with interaction Ĥint = ∑i,j ∑νγij(ν) σi ⊗ σj(ν) with random γij to investigate the effect of intra-environmental coupling on the central spin. By changing the dynamics of the environment its effect as a bath on the central spin is changed and may even be adjustable to some degree. The relaxation behavior is related to the distribution of the energy eigenvectors of the total system.