Figure 2: Thermal motion measured via the quantum dot current.
From: Gate-controlled electromechanical backaction induced by a quantum dot
(a) A schematic of the experimental setup for measuring thermal motion of the mechanical resonator. The potential fluctuation Δϕ induced by the piezoelectric field associated with the mechanical thermal motion results in current fluctuations, which are fed into a load resistor RL=1 kΩ and the voltage drop across the load is amplified by cryogenic (G1) and room-temperature (G2) amplifiers (see Methods). The resultant amplified signal is measured with a spectrum analyser. (b–d) The current power spectral density SI around f0 at three different temperature. The bold solid line shows a Lorenzian fit, from which the peak area A corresponding to the squared amplitude of the mechanical motion is obtained. (e,f) Temperature dependence of the transconductance gm≡dI/dVsd (e) and A normalized by gm (f) along with a linear fit (solid line).
