Gatemon Benchmarking and Two-Qubit Operation*

Recent experiments have demonstrated superconducting transmon qubits with semiconductor nanowire Josephson junctions \footnote{G. de Lange et al., Physical Review Letters \textbf{115}, 127002 (2015).} \footnote{T. W. Larsen, K. D. Petersson et al., Physical Review Letters \textbf{115}, 127001 (2015).}. These hybrid gatemon qubits utilize field effect tunability singular to 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 of $\sim$0.5~\% 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 $\sim$91~\%, demonstrating the potential of gatemon qubits for building scalable quantum processors.