Voltage-activated parametric entangling gates based on gatemon qubits
Yinqi Chen, Konstantin Nesterov, Hugh Churchill, Javad Shabani, Vladimir Manucharyan, Maxim Vavilov · Physical Review Applied · 2023
We describe the generation of entangling gates on superconductor-semiconductor hybrid qubits by ac voltage modulation of the Josephson energy. Our numerical simulations demonstrate that the unitary error can be below ${10}^{\ensuremath{-}5}$ in a variety of 75-ns-long two-qubit gates (CZ, $i\mathrm{SWAP}$, and $\sqrt{i\mathrm{SWAP}}$) implemented using parametric resonance. We analyze the conditional $ZZ$ phase and demonstrate that the CZ gate needs no further phase-correction steps, while the $ZZ$ phase error in swap-type gates can be compensated by choosing pulse parameters. With decoherence considered, we estimate that qubit relaxation time needs to exceed $70\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}\mathrm{s}$ to achieve the 99.9% fidelity threshold.