Gatemon Benchmarking and Two-Qubit Operation

TL;DR

This paper reports on the development and characterization of a two-qubit gatemon circuit, demonstrating high-fidelity single-qubit gates, coherent coupling, and a two-qubit controlled-phase gate with promising implications for scalable quantum computing.

Contribution

It introduces a two-qubit gatemon architecture with detailed coherence, stability, and gate fidelity measurements, showcasing its potential for scalable quantum processors.

Findings

Single-qubit gate errors below 0.7%

Coherent capacitive coupling between gatemons

Two-qubit controlled-phase gate with 91% fidelity

Abstract

Recent experiments have demonstrated superconducting transmon qubits with semiconductor nanowire Josephson junctions. These hybrid gatemon qubits utilize field effect tunability characteristic for semiconductors to allow complete qubit control using gate voltages, potentially a technological advantage over conventional flux-controlled transmons. Here, we present experiments with a two-qubit gatemon circuit. We characterize qubit coherence and stability and use randomized benchmarking to demonstrate single-qubit gate errors below 0.7% for all gates, including voltage-controlled $Z$ rotations. We show coherent capacitive coupling between two gatemons and coherent swap operations. Finally, we perform a two-qubit controlled-phase gate with an estimated fidelity of 91%, demonstrating the potential of gatemon qubits for building scalable quantum processors.