Microwave excitation and readout of nano- and micron scale cantilevers

We show that a microwave near-field coaxial resonator system allows mechanical cantilever excitation on a scale much shorter than the microwave wavelength. Thermal noise is observed in the unexcited system, enabling room temperature displacement sensitivity of ∼70 fm/Hz1/2. The measured force between near-field probe and cantilever varies with separation, in excellent agreement with theory. Uniquely, optical excitation and read-out lasers are also included. The dependence of mechanical resonator quality factor on ambient air pressure has been accurately measured. We have demonstrate passive cantilever mode cooling from 300 K to 80 K by frequency detuning the microwave resonator and propose pulsed cooling operation to enable several high-sensitivity applications.

Research highlights► Microwave near-field allows cantilever excitation on a scale less than microwave λ. ► We show that at room temperature our system displacement sensitivity ∼70 fm/Hz1/2. ► Measured force between near-field probe and cantilever agreed with theory. ► The dependence of mechanical resonator Q on pressure accurately measured. ► We have demonstrated passive cantilever mode cooling from 300 K to 80 K.