Berlin 2015 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 7: Transport: Quantum coherence and quantum information systems - Theory (TT with HL)
HL 7.13: Talk
Monday, March 16, 2015, 12:45–13:00, H 3005
Spin dynamics using the Majorana representation: validity, path integral and higher correlators — •Pablo Schad1, Boris N. Narozhny1,2, Gerd Schön3, Yuriy Makhlin4,5, 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 und Institut für Nanotechnologie, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany — 4Landau Institute for Theoretical Physics, acad. Semyonov av., 1a, 142432, Chernogolovka, Russia — 5Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Russia
We present a method to calculate higher spin correlators via the Majorana fermion representation of spin operators. We show explicitly that the Majorana representation does not require any projection procedure. Previously found identities [1,2] between spin and Majorana fermion correlation functions are extended. As an example we consider a spin-1/2 coupled to an isotropic, ohmic bath. We formulate a path-integral approach, which is valid at B=0 in contrast to perturbation theory, find the saddle-point solution and discuss fluctuations. We demonstrate that spin correlators in the high-temperature regime can be obtained using saddle-point Green’s functions.
[1] A. Shnirman and Y. Makhlin,
Phys. Rev. Lett. 91, 207204 (2003).
[2] W. Mao, P. Coleman, C. Hooley, and D. Langreth,
Phys. Rev. Lett. 91, 207203 (2003).