Dephasing in Open Quantum Dots

TL;DR

This paper measures electron phase coherence times in open ballistic GaAs quantum dots using shape-averaged magnetoconductance, revealing unexpected temperature dependence and agreement with disordered 2D electron system models.

Contribution

First application of shape-averaged magnetoconductance to determine $ au_{phi}$ in open quantum dots, showing novel temperature independence and theoretical agreement.

Findings

$ au_{phi}$ is independent of dot area from 0.335 to 4 K.

Observed $ au_{phi}(T)$ does not follow the expected $T^{-2}$ behavior.

$ au_{phi}(T)$ matches predictions for disordered 2D electron systems.

Abstract

Shape-averaged magnetoconductance (weak localization) is used for the first time to obtain the electron phase coherence time $\tau_{\phi}$ in open ballistic GaAs quantum dots. Values for $\tau_{\phi}$ in the range of temperature T from 0.335 to 4 K are found to be independent of dot area, and are not consistent with the $\tau_{\phi} \propto T^{-2}$ behavior expected for isolated dots. Surprisingly, $\tau_{\phi}(T)$ agrees quantitatively with the predicted dephasing time for disordered two-dimensional electron systems.