Suppressing spurious transitions using spectrally balanced pulse

TL;DR

This paper presents a spectrally balanced pulse technique that significantly reduces unwanted transitions in superconducting qubits, improving quantum gate fidelity and enabling better control in large-scale quantum systems.

Contribution

The authors introduce a novel pulse-shaping method using spectrally balanced microwave pulses to suppress spurious transitions in superconducting qubits.

Findings

Order-of-magnitude reduction in spurious excitations between weakly detuned qubits

Substantial decrease in single-qubit gate errors caused by two-level defects

Broadband suppression of undesired transitions across frequency ranges

Abstract

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 work, 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 to mitigate adverse effects from parasitic couplings, enhancing the fidelity of quantum operations and expanding feasible frequency allocations for large-scale quantum devices.