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. 2015 Apr 27;6:6981. doi: 10.1038/ncomms7981

Figure 3. Optomechanics enhanced by a qubit.

Figure 3

(a,b) Optical spring effect as a function of gate charge. The solid lines are a fit to theory and are plotted in the region where detuning and coupling are such that the peaks are visible. The red and blue colours refer to the two cavity branches as in Fig. 2. The black circles present data that presumably originate from higher excited levels of the qubit (see main text). The pump frequency ωp/2π=4.79 GHz, and the sideband (ωp+ωm)/2π=4.855 GHz. (c) Illustration of the pump detuning for the two branches for the measurements in a and b. (d) Radiation-pressure coupling extracted from ωc(ng). (e) Optical spring as a function of pump detuning, at fixed gate charge ng=0.25. The solid line is a fit to theory. In all data, the cavity photon number is in the range 0.1...1. This is estimated based on the input power and cable attenuation, and in the end fine-tuned as an adjustable parameter. In all the panels, Vg=4.6 V.