a Pulse cycles used for the randomized benchmarking experiments. The measurement pulse cycle consists of m gates randomly drawn from the Clifford group C rand and a final Clifford gate projecting the qubit onto the spin-up state. The reference pulse cycle consists of the same m Clifford gates and a different final Clifford gate projecting the qubit onto the spin-down state. Each cycle is repeated N times, and a series of typically k = 50 independent randomly drawn measurement and reference pulse cycles are alternated. These k = 50 different draws are thus hardware-averaged on the lock-in amplifier, and the entire experiment is repeated and averaged 30 times, yielding a total approximate 105 repetitions of 1,500 different randomly drawn Clifford sequences of length m. An example of the qubit evolution for each pulse cycle is plotted on the Bloch sphere below. b, Pulse cycles used for the exchange mapping experiments. The measurement pulse cycle consists of a broad preparation and restoring pulse at frequency f 3 (f 1 ), around a probing pulse at frequency f prb . The reference pulse cycle consists solely of the probing pulse at f prb . The qubit evolutions for the different resonance conditions are plotted on the Bloch sphere and illustrate the different signals measured in Fig. 4c, d.