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TT: Tiefe Temperaturen

TT 37: Transport - Fluctuations and Noise

TT 37.5: Talk

Wednesday, March 9, 2005, 11:15–11:30, TU H3027

Correlations in noisy Landau-Zener transitions — •Stefan Scheidl¹ and Valery L. Pokrovsky^2,3 — ¹Institut für Theoretische Physik, Universität zu Köln — ²Department of Physics, Texas A&M University, College station — ³Landau Institute for Theoretical Physics, Chernogolovka

We analyze the influence of colored classical Gaussian noise on Landau-Zener transitions during a two-level crossing in a time-dependent regular external field [1]. Transition probabilities and coherence factors become random due to the noise. We calculate their two-time correlation functions, which describe the response of this two-level system to a weak external pulse signal. The spectrum and intensity of the magnetic response are derived. Although the noise enters the equation of motion for the Bloch vector in a multiplicative way, non-perturbative analytic results are obtained by a resummation of diagrams in the limit of a short noise correlation time. Our results also cover regimes where fluctuations are of the same order of magnitude as averages.

[1] V.L. Pokrovsky and S. Scheidl, Phys. Rev. B 70, 014416 (2004)