a, Pulse diagram of the echoed CR sequence including the rotary echoes applied to the target qubit. The sampling time is 0.2222 ns per sample. ‘d10’ and ‘d12’ denote the drive channels for qubits Q10 and Q12 respectively, while ‘u21’ denotes the cross-resonance channel for the control qubit, 10. b, Fine amplitude calibration of the echoed ZXπ/4 CR pulse sequence for qubits Q15 and Q12. Initially the ZXπ/4 pulses are applied in repetitions of 2 to ensure a full rotation about the Bloch sphere. At 16 repetitions, the pulses are applied in repetitions of 4 to apply π pulses about the Bloch sphere equator in order to amplify amplitude errors. c, Rabi oscillations of the target qubit used to calibrate a 2π rotary echo for Q12.