Super-Poissonian Shot Noise as a Measure of Dephasing in Closed Quantum Dots

TL;DR

This paper proposes using the super-Poissonian shot noise, specifically the Fano factor peak, as a novel method to measure dephasing rates in closed quantum dots, which are crucial for quantum computing applications.

Contribution

It introduces a new approach to measure dephasing in closed quantum dots by analyzing the Fano factor peak in shot noise, linking it to the dephasing rate.

Findings

Fano factor exhibits a sharp peak related to dephasing rate

Peak position can be used to quantify dephasing

Method applicable to mesoscopic quantum systems

Abstract

Electron-electron interactions play a major role in determining the low-temperature rate of phase loss of electrons in mesoscopic systems. The study of the dephasing rate is expected to contribute to the understanding of the many-body nature of such systems. Closed quantum dots are of special interest in this respect, due to theoretical predictions suggesting a possible transition temperature below which the dephasing rate vanishes. This prediction has attracted much attention, since closed quantum dots are prime candidates for storage units in quantum computers, and thus their phase coherence properties are of great importance. However, an effective method for measuring the dephasing rate within a closed quantum dot is still lacking. Here we study two-level systems and show that the Fano factor has a sharp peak as a function of the chemical potential, the location of which can be simply related to the dephasing rate. We thus suggest to use the properties of the Fano factor peak in the super-Poissonian regime as a probe for the dephasing rate.