Voltage-tunable, femtometer-precision cantilever displacement and squeezing in a plasmomechanical system

Abstract

We present an elegant method for continuous electrical-tuning of the cantilever position in a plasmomechanical system without changing the plasmonic gap size. Cantilever is the mechanical oscillator coupled to the plasmonic gap intensity. The same method allows the voltage-tuning of the uncertainty in the cantilever position (quadrature squeezing). Recent experiments achieve nanometer-scale bending of cantilevers using electrostatic actuators. Unlike those works, we do not bend the cantilever, which can introduce noise into the oscillations and limit the response time. Instead, we electrically tune the intensity in the plasmonic gap, thus the plasmomechanical coupling, through Fano resonance. This allows continuous control of the cantilever position in units of the mechanical oscillator's natural length, which is about 30 fm in those experiments. Using this approach, the coupling strength can be varied by 2 orders-of-magnitude with a voltage change of only 1 V. The response time is in the picosecond range.