Nonsaturating Dephasing Time at Low Temperature in an Open Quantum Dot

TL;DR

This study measures electron dephasing times in an open quantum dot at very low temperatures, finding no saturation and a clear inverse linear temperature dependence, challenging previous results.

Contribution

It provides the first clear observation of non-saturating dephasing times in open quantum dots at millikelvin temperatures, confirming theoretical predictions.

Findings

Dephasing time does not saturate at low temperatures.

Dephasing time follows an inverse linear power law with temperature.

Extraction methods are effective down to 13 mK, despite charging effects.

Abstract

We report measurements of the electron dephasing time extracted from the weak localization (WL) correction to the average conductance in an open AlGaAs/GaAs quantum dot from 1 K to 13 mK. In agreement with theoretical predictions but in contrast with previous measurements in quantum dots, the extracted dephasing time does not saturate at the lowest temperatures. We find that the dephasing time follows an inverse linear power law with temperature. We determine that the extraction of the dephasing time from WL is applicable down to our lowest temperatures, but extraction from finite magnetic field conductance fluctuations is complicated by charging effects below 13 mK.