Figure 3: Backaction effects as a function of QD bias conditions.
From: Gate-controlled electromechanical backaction induced by a quantum dot
(a–c) Colour plots of frequency shift f−f0, quality factor Q and differential conductance G as a function of Vsd and Vg. These plots correspond to the Vsd and Vg region as indicated by the blue square in Fig. 1e and Vg0=−0.465 V is the gate voltage at which the Coulomb peak is positioned, where the dashed lines indicate the Coulomb diamond. (d–i) Comparison of the mechanical backaction effects between Vsd=0 mV (d–f) and Vsd=0.48 mV (g–i). In Vsd=0 mV, a linear f-shift, as indicated by the dashed line, as well as a f-dip at Vg=Vg0 is observed, whereas no deviation is found in the corresponding Q-factor as I=0. At finite Vsd, both frequency and Q-factor are modulated around the Coulomb peak, indicating the presence of a backaction force from the local charge state in the QD. Red (blue) area in h highlights the enhancement (suppression) of Q-factor. Schematics in (f,i) depict the corresponding energy diagram in the QD and the leads. In f, the relevant single electron level is above (below) the unbiased electrochemical potential when Vg<Vg0 (Vg>Vg0). In i, the electron energy level moves across the electrochemical potential in the source (drain) electrode when Vg<Vg0 (Vg>Vg0).
