Dresden 2003 – wissenschaftliches Programm

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SYQD: Quantum decoherence in solid state physics

SYQD 1: Quantum Decoherence in Solid State Physics I

SYQD 1.6: Hauptvortrag

Dienstag, 25. März 2003, 16:30–17:00, HSZ/01

Decoherence of Interacting Electrons in Disordered Conductors: on the Relation between Influence Functional and diagrammatic approaches — •Jan von Delft — Sektion Physik und Center for NanoScience der Ludwig-Maximilians-Universität München, 80333, München, Germany

A few years ago, Golubev and Zaikin (GZ) developed an influence functional approach (reviewed in [1]) for describing interacting fermions in a disordered conductor: the diffusive motion of an electron interacting with its environment (other electrons) is captured in an effective action i S_R + S_I, which in principle correctly accounts for the Pauli principle (via S_R). GZ used their approach to calculate the electron decoherence time τ_φ(T), and found it to be finite at zero temperature: τ_φ(T → 0) = τ_ϕ⁰. This contradicts the standard view, based on the work of Altshuler, Aronov and Khmelnitskii, that τ_φ(T → 0)= ∞. In this talk, I shall review the various recent (and controversial [2]) calculations of τ_φ. I conclude [3] that
(i) GZ’s influence functional is in principle consistent with standard Keldysh diagrammatic perturbation theory; but
(ii) when applying their influence functional, GZ obtain a finite τ_φ⁰ because they make a semiclassically-motivated approximation which violates the Pauli principle (concretely, they claim that S_R can be neglected when calculating τ_φ⁰). I argue that this approximation breaks down at low temperatures.

[1] D. S. Golubev, A. D. Zaikin, and G. Schön, cond-mat/0110495.

[2] Aleiner et al., cond-mat/9808053, cond-mat/0110545.

[3] Jan von Delft, cond-mat/0210644.