Figure 3. Dynamical backaction cooling with electrons.

(a) Schematic introducing the notations used in the text. The electron probe (blue spot) is at the average position (x_p,eq, y_p). The dynamical displacement δx_p around the position of the probe and the tip displacement δx are related via the mode shape function u of the nanowire. (b) Dynamical backaction cooling using an electron beam. The longitudinal position of the electron spot is scanned across the entire nanowire length (left), with the transverse coordinate x_p,eq being fixed. For each point, the corresponding fluctuation spectrum is recorded (acquisition time ≃2 min). The presented data are normalized to the same effective mass, to better visualize the drastic decrease of the effective temperature. Straight lines are a double Lorentzian adjustment of the experimental data. We attribute the observed amplification of the out-of-plane mode (left most peak) to the presence of orthogonal gradients. (c) Effective temperature (green squares) and effective damping rate (black dots) as functions of the effective mass. The straight lines correspond to plots of our theoretical model (equation 4), yielding Γ_e(x_p,eq)/2π=604 Hz.