<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Z</mml:mi><mml:mi>Z</mml:mi></mml:mrow></mml:math>-interaction-free single-qubit-gate optimization in superconducting qubits
Shu Watanabe, Yutaka Tabuchi, Kentaro Heya, Shuhei Tamate, Yasunobu Nakamura
Abstract
Overcoming the issue of qubit-frequency fluctuations is essential to realizing stable and practical quantum computing with solid-state qubits. Static $ZZ$ interaction, which causes a frequency shift of a qubit depending on the state of neighboring qubits, is one of the major obstacles to integrating fixed-frequency transmon qubits. Here we propose and experimentally demonstrate $ZZ$-interaction-free single-qubit-gate operations on a superconducting transmon qubit by utilizing a semianalytically optimized pulse based on a perturbative analysis. The gate is designed to be robust against slow qubit-frequency fluctuations. The robustness of the optimized gate spans a few megahertz, which is sufficient to suppress the adverse effects of the $ZZ$ interaction. Our result paves the way for an efficient approach to overcoming the issue of $ZZ$ interaction without any additional hardware overhead.