Suppressing Spurious Transitions Using Spectrally Balanced Pulse
Ruixia Wang, Yaqing Feng, Yujia Zhang, Jiayu Ding, Boxi Li, Felix Motzoi, Yang Gao, Huikai Xu, Zhen Yang, Wuerkaixi Nuerbolati, Haifeng Yu, Weijie Sun, Fei Yan · Physical Review Letters · 2025
Achieving precise control over quantum systems presents a significant challenge, especially in many-body setups, where residual couplings and unintended transitions undermine the accuracy of quantum operations. In superconducting qubits, parasitic interactions-both between distant qubits and with spurious two-level systems-can severely limit the performance of quantum gates. In this Letter, we introduce a pulse-shaping technique that uses spectrally balanced microwave pulses to suppress undesired transitions. Experimental results demonstrate an order-of-magnitude reduction in spurious excitations between weakly detuned qubits as well as a substantial decrease in single-qubit gate errors caused by a strongly coupled two-level defect over a broad frequency range. Our method provides a simple yet powerful solution for mitigating adverse effects from parasitic couplings, enhancing quantum gate fidelity. The pulse-shaping technique can be readily adapted to various physical systems.