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TT: Fachverband Tiefe Temperaturen
TT 103: Transport: Poster Session
TT 103.24: Poster
Donnerstag, 19. März 2015, 15:00–18:00, Poster B
Nonequilibrium spin noise and noise of susceptibility — •Pablo Schad1, Boris N. Narozhny1,2, Gerd Schön3,4, and Alexander Shnirman1 — 1Institut für Theorie der Kondensierten Materie, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany — 2National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, 115409 Moscow, Russia — 3Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany — 4Institut für Nanotechnologie, Karlsruhe Institute of Technology, D-76021 Karlsruhe, Germany
We analyze out-of-equilibrium fluctuations in a driven spin system and relate them to the noise of spin susceptibility. In the spirit of the linear response theory we further relate the noise of susceptibility to a 4-spin correlation function in equilibrium. We show that, in contrast to the second noise (noise of noise), the noise of susceptibility is a direct measure of non-Gaussian fluctuations in the system. We develop a general framework for calculating the noise of susceptibility using the Majorana representation of spin-1/2 operators. We illustrate our approach by a simple example of noninteracting spins coupled to a dissipative (Ohmic) bath.
[1] P. Schad, B. N. Narozhny, G. Schön, and A. Shnirman,
Phys. Rev. B 90, 205419 (2014).