Fig. 6: Sideband cooling of the mechanical memory mode.

a The ringdown measurement of total mechanical linewidth γtot with a set of sideband cooling powers P. Colored-solid dots are experiment data and black-solid curves represent the fitting. b Cavity-field backaction introduces an additional optical-damping γopt for the mechanical resonator. γopt exhibits a linear growth with increasing the sideband driving power P. c The mechanical occupation is calibrated as the number of motional quanta. \({N}_{{{{\rm{m}}}}}^{{{{\rm{th}}}}}\) (\({N}_{{{{\rm{c}}}}}^{{{{\rm{th}}}}}\)) is the effective thermal bath occupation of the mechanical mode (microwave cavity mode), respectively. Error bars equal one standard deviation.