Automated in Situ Optimization and Disorder Mitigation in a Quantum Device
Jacob Benestad (Norwegian University of Science and Technology (NTNU))
Torbjørn Rasmussen (Kavli institute of nanoscience Delft, University of Copenhagen, TU Delft - QRD/Chatterjee Lab, TU Delft - QuTech Advanced Research Centre)
Bertram Brovang (University of Copenhagen)
Oswin Krause (University of Copenhagen)
Saeed Fallahi (Purdue University)
Geoffrey C. Gardner (Purdue University)
Charles M. Marcus (University of Copenhagen)
Anasua Chatterjee (University of Copenhagen, TU Delft - QRD/Chatterjee Lab, TU Delft - QuTech Advanced Research Centre, TU Delft - QN/Chatterjee Lab, Kavli institute of nanoscience Delft)
Evert Van Nieuwenburg (Universiteit Leiden)
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Abstract
We investigate automated in situ optimization of the potential landscape in a quantum point contact device, using a 3×3 gate array patterned atop the constriction. Optimization is performed using the covariance matrix adaptation evolutionary strategy, for which we introduce a metric for how "steplike"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.