Automated in situ optimization and disorder mitigation in a quantum device

Abstract

We investigate automated in situ optimization of the potential landscape in a quantum point contact device, using a $3\times 3$ gate array patterned atop the constriction. Optimization is performed using the covariance matrix adaptation evolutionary strategy, for which we introduce a metric for how "step-like" the conductance is as the channel becomes constricted. We first perform the optimization of the gate voltages in a tight-binding simulation and show how such in situ tuning can be used to mitigate a random disorder potential. The optimization is then performed in a physical device in experiment, where we also observe a marked improvement in the quantization of the conductance resulting from the optimization procedure.

8 pages, 4 figures (supplement: 6 pages, 4 figures)