Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 29: Transport: Quantum Coherence and Quantum Information Systems - Part 1

TT 29.1: Hauptvortrag

Donnerstag, 30. März 2006, 09:30–10:00, HSZ 304

Decoherence of fermions subject to a quantum bath — •Florian Marquardt — Sektion Physik, Arnold Sommerfeld Center for Theoretical Physics, und Center for NanoScience, Ludwig-Maximilians-Universität München, Theresienstr. 37, 80333 München

The destruction of quantum-mechanical phase coherence by a fluctuating environment is both of fundamental interest and essential for applications of quantum dynamics. While the theory of decoherence is well developed for a two-level system or a single particle, the case of many fermions is less understood, despite its relevance for nanoelectronics.

After giving a general introduction, I will focus on the analysis of decoherence in the most basic interferometer, the Mach-Zehnder setup, whose electronic version has been been realized only recently [1]. Based on our earlier work on the influence of classical noise [2], we have studied the case of a fully quantum-mechanical environment [3]. Using a novel equations-of-motion approach, we have calculated the dephasing rate, including many-body effects like Pauli blocking. I will give a transparent physical interpretation of the results, describe related work on weak localization [4], and discuss the shot noise in the output current.

[1] Y. Ji et al., Nature 422, 415 (2003); I. Neder et al., cond-mat/0508024.

[2] F. Marquardt and C. Bruder, Phys. Rev. Lett. 92, 056805 (2004); Phys. Rev. B 70, 125305 (2004).

[3] F. Marquardt, cond-mat/0410333, to appear in Europhys. Lett. (Dec. 2005).

[4] F. Marquardt, J. v. Delft, R. Smith, and V. Ambegaokar, cond-mat/0510556.