Correcting on-chip distortion of control pulses with silicon spin qubits

TL;DR

This paper introduces two calibration techniques to correct pulse distortions in silicon spin qubits, significantly enhancing control accuracy and gate fidelity in quantum dot systems.

Contribution

It presents the first effective calibration procedures using the two-qubit system as a detector to correct on-chip pulse distortions in silicon spin qubits.

Findings

The all predistortion (APD) method significantly improves exchange oscillation homogeneity.

APD enables accurate delivery of arbitrary control waveforms.

Coarse predistortion (CPD) provides partial correction of pulse distortions.

Abstract

Pulse distortion, as one of the coherent error sources, hinders the characterization and control of qubits. In the semiconductor quantum dot system, the distortions on measurement pulses and control pulses disturb the experimental results, while no effective calibration procedure has yet been reported. Here, we demonstrate two different calibration methods to calibrate and correct the distortion using the two-qubit system as a detector. The two calibration methods have different correction accuracy and complexity. One is the coarse predistortion (CPD) method, with which the distortion is partly relieved. The other method is the all predistortion (APD) method, with which we measure the transfer function and significantly improve the exchange oscillation homogeneity. The two methods use the exchange oscillation homogeneity as the metric and are appropriate for any qubit that oscillates with a diabatic pulse. With the APD procedure, an arbitrary control waveform can be accurately delivered to the device, which is essential for characterizing qubits and improving gate fidelity.