Long dephasing time and high temperature ballistic transport in an InGaAs open quantum dot

TL;DR

This study demonstrates that an InGaAs quantum dot exhibits long electron dephasing times and supports ballistic transport at high temperatures, with implications for quantum device performance.

Contribution

It provides the first detailed measurement of magnetoconductance in InGaAs quantum dots, revealing long coherence times and ballistic transport behavior at elevated temperatures.

Findings

Electron phase coherence time exceeds that in GaAs/AlGaAs quantum dots.

Ballistic transport persists up to 204K.

Distinct temperature dependence of focusing fluctuations below 150K.

Abstract

We report on measurements of the magnetoconductance of an open circular InGaAs quantum dot between 1.3K and 204K. We observe two types of magnetoconductance fluctuations: universal conductance fluctuations (UCFs), and 'focusing' fluctuations related to ballistic trajectories between openings. The electron phase coherence time extracted from UCFs amplitude is larger than in GaAs/AlGaAs quantum dots and follows a similar temperature dependence (between T^-1 and T^-2). Below 150K, the characteristic length associated with 'focusing' fluctuations shows a slightly different temperature dependence from that of the conductivity.