Fast raster scan multiplexed charge stability measurements toward high-throughput quantum dot array calibration

Abstract

We report raster scan multiplexed charge-stability diagram measurements for tuning multiple gate-defined quantum dots in GaAs/AlGaAs heterostructures. We evaluate the charge sensitivity of the quantum point contact (QPC) in both radio frequency (rf)-reflectometry and direct current-transport modes, where we measure the signal-to-noise ratio (SNR) of 40 for rf-QPC with an integration time per pixel of 10 ms, corresponding to 1.14 ms for resolving single electron transition in the few electron regime. The high SNR for reasonable integration time allows fast two-dimensional (2D) scanning, which we use to facilitate double and triple quantum dot (TQD) tuning processes. We configure a highly stable raster scan multiplexed quantum dot tuning platform using a switching matrix and transformer-coupled alternating current ramp sources with software control. As an example of high-throughput multiple quantum dot tuning, we demonstrate systematic TQD formation using this platform in which a multiplexed combination of 2D scans enables the identification of the few electron regime in multiple quantum dots in just a few minutes. The method presented here is general, and we expect that the tuning platform is applicable to more complex multiple quantum dot arrays, allowing efficient quantum dot system Hamiltonian parameter calibration.