Fig. 1: Concept.
From: Single-photon induced instabilities in a cavity electromechanical device
a A schematic of a quarter wavelength coaxial cavity (red) coupled to a transmon (yellow). The two pads provide the shunting capacitance as well as coupling capacitance to the cavity. The axial and normal components of the magnetic field are denoted by B∥ and B⊥, respectively. b A tilted false-color scanning electron microscope image of the SQUID loop with embedded mechanical resonator. The suspended Al nanomechanical resonator can be seen. The Al film and the silicon substrate are shown in yellow and gray colors, respectively. The selective-etched region used to suspend the mechanical resonator is shown by the cyan-colored region. The mechanical resonator has dimensions of 40 μm × 200 nm × 28 nm. c A representative color plot of the voltage transmission ∣S21∣ through the cavity as the magnetic flux through the SQUID loop is varied. d The panel shows a linecut from panel (c), corresponding to Φ/Φ0 = 0.27(0.5) in green (yellow) emphasizing the vacuum-Rabi split peaks (dressed-cavity peak). The solid lines are complex Lorentzian fits and plotted as a guide to the eye. e A schematic to depict the change in frequency of the dressed modes as the magnetic flux is swept. The gradual color shift from blue to red or vice versa indicates how the nonlinear character of the mode is changing with flux.
