Extended Data Fig. 7: Control experiment with and without qubit modulation.

Each panel shows the measured qutrit population with time for two different catch protocols. Inset pulse sequences illustrate the differences between the two experiments. a, a single phonon is released from Q₁ and partially reflected by the BS. During the subsequent catch process, we use the qubit modulation pulse sequence shown in Fig. 4c. b, Catch process using the time-reversed control for the release process. Both experiments yield similar catch efficiencies (0.32 vs. 0.34). We observe no spurious phonon excitation to the transmon \(\left\vert\;f\;\right\rangle\) state, with or without qubit modulation.