  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.
