Dresden 2011 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 26: TR: Fluctuations and Noise

TT 26.5: Vortrag

Dienstag, 15. März 2011, 15:15–15:30, HSZ 301

Thermal noise due to electron interactions in networks of disordered wires — •Maximilian Treiber¹, Christophe Texier², Oleg M. Yevtushenko¹, Jan von Delft¹, and Igor V. Lerner³ — ¹Ludwig-Maximilians-Universität, Physics Department, ASC, CeNS, Theresienstrasse 37, D-80333 Munich, Germany — ²Université Paris-Sud, CNRS, LPTMS, UMR 8626, Bat. 100, F-91405 Orsay, France — ³University of Birmingham, School of Physics and Astronomy, Birmingham, B15 2TT, UK

At sufficiently low temperatures, electron interactions govern dephasing in mesoscopic samples. Thus, a theory of dephasing requires the knowledge of the correlation function of Johnson-Nyquist (electronic) noise. This function is well-known, for example, for quasi-1d wires. Recent experiments address dephasing in substantially inhomogeneous systems consisting of multiply-connected wires, such as metallic grids or connected rings. Motivated by these experiments, we study the spatial dependence of the noise correlation function in networks of disordered wires with arbitrary boundary conditions.

Using the fluctuation-dissipation theorem and the random-phase approximation, we derive a real-space integro-differential equation for the correlation function. In the case of sufficiently strong screening, this equation reduces to a time-integrated diffusion equation which has to be solved for the given boundary conditions (such as connections to leads). We show how a solution can be found efficiently for networks of wires, by using a method based on the spectral determinant.