Voltage Activated Parametric Entangling Gates on Gatemons

TL;DR

This paper presents a method for generating high-fidelity entangling gates on superconductor-semiconductor hybrid qubits using ac voltage modulation, with simulations showing errors below 10^-5 and conditions for optimal performance.

Contribution

It introduces a novel approach to implement entangling gates via parametric resonance in gatemon qubits, achieving low error rates without additional phase correction.

Findings

Unitary error below 10^-5 in 75-ns gates

CZ gate requires no phase correction

Qubit relaxation time >70μs needed for 99.9% fidelity

Abstract

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, $i$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 $70\mu\mathrm{s}$ to achieve the 99.9% fidelity threshold.