Interactions and Quantum Decoherence in the Ground State: Persistent Currents and Weak Localization

ĽAndrei D. Zaikin1, D. S. Golubev2 und C. P. Herrero3
1Forschungszentrum Karlsruhe, Institut für Nanotechnologie, 76021 Karlsruhe, Germany
2Institut für Theoretische Festkörperphysik, Universität Karlsruhe, 76128 Karlsruhe, Germany
3Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid, Spain

We will address the fundamental question of interaction-induced quantum decoherence at zero temperature.

In the first part of the talk we will analyse the phenomenon of rersistent currents in mesoscopic rings. Combining non-perturbative techniques with Monte Carlo simulations we will demonstrate that quantum coherence effects for a particle on a ring are suppressed beyond a finite length Lj, even at zero temperature, if the particle is coupled to a diffusive electron gas by means of long range Coulomb interaction. This length is consistent with Lj derived from weak-localization-type of analysis.

In the second part of the talk we will analyse the weak localization correction dswl to the conductance of a disordered metal employing no approximations beyond the accuracy of the definition of dswl. Our analysis applies to all orders in the electron-electron interaction and extends our previous calculation by explicitly taking into account quantum fluctuations around the classical paths for interacting electrons (pre-exponent). We will specifically address the low-temperature limit and demonstrate that such fluctuations can only be important in the perturbative regime of short times while they are practically irrelevant for the Cooperon dynamics at longer times. Special attention will be paid to the role of the Pauli principle which will be proven essentially irrelevant for the electron decoherence at low temperatures.

Our analysis fully confirms the conclusion about the existence of interaction-induced decoherence of electrons at zero temperature for the problem in question.