Towards autonomous time-calibration of large quantum-dot devices: Detection, real-time feedback, and noise spectroscopy

TL;DR

This paper presents an autonomous calibration method for large quantum-dot arrays that uses charge stability diagrams for real-time stabilization, noise spectroscopy, and diagnostics, improving scalability and qubit performance.

Contribution

The authors introduce a novel autonomous stabilization framework using charge transition tracking and noise spectroscopy for large quantum-dot devices, enabling scalable quantum processor calibration.

Findings

Robust stabilization of a 10-QD device achieved.

Real-time noise spectral analysis performed successfully.

Identified dominant noise sources and spatial correlations.

Abstract

The performance and scalability of semiconductor quantum-dot (QD) qubits are limited by electrostatic drift and charge noise that shift operating points and destabilize qubit parameters. As systems expand to large one- and two-dimensional arrays, manual recalibration becomes impractical, creating a need for autonomous stabilization frameworks. Here, we introduce a method that uses the full network of charge-transition lines in repeatedly acquired double-quantum-dot charge stability diagrams (CSDs) as a multidimensional probe of the local electrostatic environment. By accurately tracking the motion of selected transitions in time, we detect voltage drifts, identify abrupt charge reconfigurations, and apply compensating updates to maintain stable operating conditions. We demonstrate our approach on a 10-QD device, showing robust stabilization and real-time diagnostic access to dot-specific noise processes. The high acquisition rate of radio-frequency reflectometry CSD measurements also enables time-domain noise spectroscopy, allowing the extraction of noise power spectral densities, the identification of two-level fluctuators, and the analysis of spatial noise correlations across the array. From our analysis, we find that the background noise at 100~$\mu$\si{\hertz} is dominated by drift with a power law of $1/f^2$, accompanied by a few dominant two-level fluctuators and an average linear correlation length of $(188 \pm 38)$~\si{\nano\meter} in the device. These capabilities form the basis of a scalable, autonomous calibration and characterization module for QD-based quantum processors, providing essential feedback for long-duration, high-fidelity qubit operations.