Force sensitivity of multilayer graphene optomechanical devices.

P Weber,J Güttinger,A Noury,J Vergara-Cruz,A Bachtold

doi:10.1038/ncomms12496

Abstract

Mechanical resonators based on low-dimensional materials are promising for force and mass sensing experiments. The force sensitivity in these ultra-light resonators is often limited by the imprecision in the measurement of the vibrations, the fluctuations of the mechanical resonant frequency and the heating induced by the measurement. Here, we strongly couple multilayer graphene resonators to superconducting cavities in order to achieve a displacement sensitivity of 1.3 fm Hz−1/2. This coupling also allows us to damp the resonator to an average phonon occupation of 7.2. Our best force sensitivity, 390 zN Hz−1/2 with a bandwidth of 200 Hz, is achieved by balancing measurement imprecision, optomechanical damping, and measurement-induced heating. Our results hold promise for studying the quantum capacitance of graphene, its magnetization, and the electron and nuclear spins of molecules adsorbed on its surface.

Highlights

Mechanical resonators based on low-dimensional materials are promising for force and mass sensing experiments
An additional difficulty in characterizing mechanical vibrations is related to the fluctuations of the mechanical resonant frequency, called frequency noise, which are sizable in small resonators endowed with high-quality factors Q10
The force sensitivity tends to be limited by measurement imprecision and frequency noise at low pump power, and by optomechanical damping and Joule heating at high pump power

Summary

Introduction

Mechanical resonators based on low-dimensional materials are promising for force and mass sensing experiments. Increasing the field in the cavity improves the readout sensitivity and eventually leads to dynamical back-action on the thermo-mechanical noise This effect has been studied intensively on comparatively large micro-fabricated resonators, resulting for instance in enhanced optomechanical damping[38,39], ground-state cooling of mechanical vibrations[40,41] and displacement imprecision below the standard quantum limit[42,43]. Another phenomenon often observed when detecting and manipulating the motion of mechanical resonators is the induced heating that can occur through Joule dissipation and optical adsorption[28,44]. The force sensitivity tends to be limited by measurement imprecision and frequency noise at low pump power, and by optomechanical damping and Joule heating at high pump power

Methods

Results

Conclusion