Tunable Coupling Architecture for Fixed-frequency Transmons
J. Stehlik, D. M. Zajac, Devin Underwood, Timothy Phung, Blair, J., Santino D. Carnevale, Klaus, D., George Keefe, April Carniol, Muir Kumph, Matthias Steffen, Oliver Dial · arXiv (Cornell University) · 2021
Implementation of high-fidelity two-qubit operations is a key ingredient for scalable quantum error correction. In superconducting qubit architectures tunable buses have been explored as a means to higher fidelity gates. However, these buses introduce new pathways for leakage. Here we present a modified tunable bus architecture appropriate for fixed-frequency qubits in which the adiabaticity restrictions on gate speed are reduced. We characterize this coupler on a range of two-qubit devices achieving a maximum gate fidelity of $99.85\%$. We further show the calibration is stable over one day.