Berlin 2012 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 13: Transport: Poster Session

TT 13.18: Poster

Montag, 26. März 2012, 15:00–19:00, Poster B

Finite Frequency Noise Spectrum of the Anderson Impurity Model — •Christoph Orth^1,2 and Andreas Komnik¹ — ¹Institut für Theoretische Physik, Universität Heidelberg — ²Department of Physics, University of Basel

Quantum noise is an inherent property for quantum information and nanoscale physics. We analyze the finite frequency current noise spectrum of a quantum dot described by a two-terminal Anderson impurity model at bias voltage V. We focus on the electron-electron interaction effects in the electron-hole symmetric case: (i) perturbatively up to the second order in the interaction strength, and (ii) using a random phase approximation for the two-particle vertex function (screened interaction) to go beyond perturbation theory. Our method is based on a non-equilibrium Keldysh Green’s function technique and is exact in tunneling.

An exact analytical formula is found for the non-interacting case which shows a staircase like structure with steps whenever ω reaches a characteristic energy of the system. The electron-electron interaction leads to non-vanishing correlations of currents with opposite spin. For small U we observe that the spectrum develops a distinct threshold at ω<−V/2 and peaks at ω≈ V/2. We expect that our results capture the generic properties of the noise spectra, which is also supported by recent publications.