Dephasing in a quantum dot coupled to a quantum point contact

TL;DR

This paper explores how charge fluctuations in a quantum point contact cause dephasing in a coupled quantum dot, explaining experimental conductance features via a model involving a quasi-bound state.

Contribution

It introduces a model linking charge fluctuations in a quasi-bound state to dephasing in a quantum dot, explaining experimental conductance peak structures.

Findings

Charge fluctuations induce dephasing in the quantum dot.

Two conducting channels explain the observed double peak.

The model accounts for experimental conductance suppression.

Abstract

We investigate a dephasing mechanism in a quantum dot capacitively coupled to a quantum point contact. We use a model which was proposed to explain the 0.7 structure in point contacts, based on the presence of a quasi-bound state in a point contact. The dephasing rate is examined in terms of charge fluctuations of electrons in the bound state. We address a recent experiment by Avinun-Kalish {\it et al.} [Phys. Rev. Lett. {\bf 92}, 156801 (2004)], where a double peak structure appears in the suppressed conductance through the quantum dot. We show that the two conducting channels induced by the bound state are responsible for the peak structure.