Figure 1: Hybrid mechanical resonator quantum dot system.
From: Gate-controlled electromechanical backaction induced by a quantum dot
(a) False-colour scanning electron microscope (FCSEM) image of the hybrid device along with the measurement setup (scale bar, 20 μm). A doubly clamped electromechanical resonator of 50 μm length, 6 μm width and 1 μm thickness is fabricated along the 
crystal axis of GaAs. (b) FCSEM image of the Schottky gate electrodes defining the quantum dot at the right clamping point of the mechanical resonator (scale bar, 1 μm). Application of negative bias voltage to these gates depletes the underlying two-dimensional electrons and confines a few electrons within a small spacial area of <300 × 300 nm2 (red circle in b). (c) Finite element method simulation of the mechanical strain associated with the fundamental flexural mode’s motion, showing the maximum strain at the clamping points. (d) The frequency response voltage power spectrum SV of the electromechanical transducer around the centre frequency f0=1664699.2 Hz of the fundamental flexural mode along with a Lorentzian fit (solid line). (e) A plot of the differential conductance of the quantum dot as a function of Vg and Vsd showing typical Coulomb diamonds as indicated by the red dashed lines. In each diamond, the number of electrons N in the QD are changed. In this study, we focus on the Coulomb peak enclosed by the blue square. (f) A Coulomb peak with the mechanical resonator under three different actuation conditions; α, no actuation; β, off-mechanical resonance actuation with Vd=150 μV at f=f0−100 Hz; γ, on-mechanical resonance actuation with Vd=150 μV.
