Fig. 3: Two-qubit process tomography and RB.
a,b, Exchange pulse diagrams and ideal process matrices of FW-CNOT (a) and SWAP (b) gates. The shading of exchange pulse boxes is proportional to the pulse exchange angle; detailed pulse angles may be found in Extended Data Tables 1 and 2. c,d, Maximum-likelihood estimates of measured quantum process matrices of FW-CNOT and SWAP gates. These data depend on joint measurement, so the relatively low M2 SPAM fidelity reduces contrast. The CNOT tomogram was measured on a similar device from the same wafer, with the same well width and gate pitch and comparable SPAM. e, Two-qubit RB with tpulse = 10 ns, tidle = 5 ns and applied magnetic field B = 2.1 mT. Individual dots represent the average from 500 shots of a single instance of a random Clifford sequence. Error bars here represent the 1σ standard deviation calculated at each Clifford length. Two-qubit Clifford gates are compiled using FW-CNOT, SWAP and single-qubit Clifford gates Cx (inset).
