Figure 1: Device and measurement setup.
From: Observation of decoherence in a carbon nanotube mechanical resonator
(a) Colourized scanning electron microscope image of a typical device, showing a suspended CNT in contact with source and drain electrodes. (b) Schematics of the measurement setup. To measure the mechanical response, two frequency signal generators are used: one for the drive and one for the probe signal. The probe signal fp is detuned by 7 MHz from the drive signal fd. A radio frequency switch is used to turn on and off the drive signal to the gate using square-wave pulses. A mixing signal is generated with a mixer at room temperature, which serves as a reference signal for the lock-in amplifier. A second mixing signal is generated by the CNT, which is impedance-matched by a high electron mobility transistor (HEMT) and detected by a lock-in amplifier. The X and Y quadrature outputs from the lock-in are recorded in sync with the switch by an oscilloscope. In the schematic, HP (LP) represent high (low) pass filters.
