Mitigating crosstalk errors in single-qubit gates on a superconducting quantum processor using analytical control pulse shaping: part 1

Microwave and hybridization crosstalk often limit the fidelity of simultaneous single-qubit gates in transmon-based quantum processing units (QPUs) due to crosstalk-induced errors in the qubit subspace and leakage to higher states. Recently, we have shown that the leakage error of sub-10-ns single-qubit gates is reduced by an order of magnitude on an individual transmon qubit using improved analytical pulse shaping techniques, such as higher-derivative (HD) DRAG [1]. In this talk, we introduce two complementary pulse shaping techniques—HD DRAG and strongly off-resonant control pulses—to mitigate microwave crosstalk on a multi-qubit QPU. We base our methods on an analytical crosstalk error model to provide intuitive insight into crosstalk mechanisms. Using off-resonant HD DRAG on a qubit pair with high crosstalk, we experimentally demonstrate an order of magnitude reduction in crosstalk-induced single-qubit gate error compared to conventional cosine DRAG pulses. The proposed techniques support efficient calibration and provide stable performance, thus paving the way for scalable crosstalk mitigation on IQM's Crystal-50 QPU as demonstrated in the part 2 of the talk.  

[1] E. Hyyppä, et al., PRX Quantum 5.3 (2024)