Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

TL;DR

This paper investigates thermally activated metastability in a GaAs double quantum dot, revealing intrinsic charge switching mechanisms that impact spin initialization and relaxation times, supported by an extended theoretical model.

Contribution

It introduces an extended double dot theory based on intrinsic thermal electron exchange, explaining observed metastabilities without external traps.

Findings

Observation of real-time charge switching in quantum dots

Thermal exchange process explains metastability

Limits on spin relaxation time set by exchange process

Abstract

We report a thermally activated metastability in a GaAs double quantum dot exhibiting real-time charge switching in diamond shaped regions of the charge stability diagram. Accidental charge traps and sensor back action are excluded as the origin of the switching. We present an extension of the canonical double dot theory based on an intrinsic, thermal electron exchange process through the reservoirs, giving excellent agreement with the experiment. The electron spin is randomized by the exchange process, thus facilitating fast, gate-controlled spin initialization. At the same time, this process sets an intrinsic upper limit to the spin relaxation time.