Fig. 2: Device modeling and characterization.
From: Deterministic multi-phonon entanglement between two mechanical resonators on separate substrates
a Numerically-calculated SAW resonator (RA and RB) characteristics. Solid lines (blue and orange) show SAW resonator electrical transmission ∣S21∣ in linear scale (left) and green dashed lines indicate the acoustic mirror reflection coefficient ∣Γ∣, with the vertical axis in dB (right), together with the real part of the IDT admittance Re(YIDT) (S) (purple dashed line), all calculated using the coupling-of-modes (COM) model59. b Qubit interaction with mechanical resonators, measured by monitoring either qubit’s excited state probability Pe (color scale) with time (vertical axis) while tuning the qubit frequency across the IDT bandwidth (horizontal axis). Interaction is measured separately for each qubit-resonator pair; response agrees well with the model using measured parameters. Blue and orange arrows indicate SAW resonant response, centered on the vacuum-Rabi exchanges of single quanta between the qubit and resonant mode. Pink arrow in right panel indicates QA idle frequency. c Simultaneous vacuum-Rabi swaps between each mechanical resonator and the associated qubit, with qubits set to the frequencies indicated by the blue and orange arrows in panel b. Solid lines are simulation results based on separate measurements of the mechanical lifetimes and qubit coherence times (See Supplementary Fig. 1). Inset shows pulse sequence (coupler control pulses not shown). Qubit populations for each data point are extracted from 3000 repetitions. Statistical uncertainties for all qubit populations are smaller than the readout infidelities (See Supplementary Table 1).
