Oscillations and fluctuations in a dissipative spin system |
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Authors: | F Shibata S Chaturvedi Y Saito |
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Institution: | (1) Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-7000 Stuttgart 80, Federal Republic of Germany;(2) Department of Physics, Ochanomizu University, Tokyo, Japan;(3) Institut für Festkörperforschung, Kernforschungsanlage Jülich GmbH, Postfach 1913, D-5170 Jülich 1, Federal Republic of Germany |
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Abstract: | A dissipative spin system, which is also considered to be a model for optical fluorescence, is investigated from the viewpoint of Brownian motion of spins. The most probable path and the fluctuations are determined by the quantum mechanical version of the system size expansion method. For the most probable path, the flow lines as well as the time evolutions are obtained exactly. This system exhibits a sort of nonequilibrium phase transition as the strength of an external field exceeds the dissipation. The fluctuations show unusual behaviour associated with the Volterra-like oscillations above threshold. |
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