Voltage-activated parametric entangling gates based on gatemon qubits

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(-5) in a variety of 75-ns-long two-qubit gates (CZ, iSWAP, and root iSWAP) 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 mu s to achieve the 99.9% fidelity threshold.