Issue
EPL
Volume 85, Number 1, January 2009
Article Number 17003
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/85/17003
Published online 07 January 2009
EPL, 85 (2009) 17003
DOI: 10.1209/0295-5075/85/17003

Decoherence and relaxation in the interacting quantum dot system

M. Q. Weng

Department of Physics, University of Science and Technology of China - Hefei, Anhui, 230026, China

weng@ustc.edu.cn

received 20 October 2008; accepted in final form 24 November 2008; published January 2009
published online 7 January 2009

Abstract
In this paper we study the low-temperature kinetics of the electrons in the system composed of a quantum dot connected to two leads by solving the equation of motion. The decoherence and the relaxation of the system caused by the gate voltage noise and electron-phonon scattering are investigated. In order to take account of the strong correlation of the electrons in this system, the quasi-exact wave functions are calculated using an improved matrix product states algorithm. This algorithm enables us to calculate the wave functions of the ground state and the low-lying excited states with satisfied accuracy and thus enables us to study the kinetics of the system more effectively. It is found that although both of these two mechanisms are proportional to the electron number operator in the dot, the kinetics are quite different. The noise-induced decoherence is much more effective than the energy relaxation, while the energy relaxation and decoherence time are of the same order for the electron-phonon scattering. Moreover, the noise-induced decoherence increases with the lowering of the dot level, but the relaxation and decoherence due to the electron-phonon scattering decrease.

PACS
72.15.Qm - Scattering mechanisms and Kondo effect.
71.27.+a - Strongly correlated electron systems; heavy fermions.
73.21.La - Quantum dots.

© EPLA 2009