Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 49: CE: Spin Systems and Itinerant Magnets 2

TT 49.3: Talk

Thursday, March 17, 2011, 14:30–14:45, HSZ 03

Spin dephasing through a nuclear spin bath — •Jasmin V. Jäger, Fabian Güttge, and Frithjof B. Anders — Technische Universität Dortmund, Lehrstuhl für Theoretische Physik II, 44221 Dortmund, Germany

In semiconducting quantum dots the electron spin coherence time is limited due to interactions of the confined electron with its environment. The most relevant decoherence mechanism in such devices is the interaction between the nuclear spins and the central electronic spin. We focus on the time-evolution of a single electron spin interacting with a bath of nuclear spins via the hyperfine interaction. Initially, the nuclear spins are unpolarized and couple to the central spin with a random distribution of hyperfine coupling constants. This central spin model has been solved exactly for a few bath spins by using the exact diagonalization method. By solving equations of motion numerically, we compute the time evolution of the electron spin interacting with a bath of nuclear spins. Because of many-particle correlations the exact equations have to be replaced by approximated equations using a cluster expansion method. In this work, we investigate the quality of the approximation by comparing the results of both methods.