  Silicon spin qubits satisfy the necessary criteria for quantum information
processing. However, a demonstration of high fidelity state preparation and
readout combined with high fidelity single- and two-qubit gates, all of which
must be present for quantum error correction, has been lacking. We use a two
qubit Si/SiGe quantum processor to demonstrate state preparation and readout
with fidelity over 97%, combined with both single- and two-qubit control
fidelities exceeding 99%. The operation of the quantum processor is
quantitatively characterized using gate set tomography and randomized
benchmarking. Our results highlight the potential of silicon spin qubits to
become a dominant technology in the development of intermediate-scale quantum
processors.
