Demonstration of Frequency Stability limited by Thermal Fluctuation Noise in Silicon Nitride Nanomechanical Resonators

Abstract

The frequency stability of nanomechanical resonators (NMR) dictates the fundamental performance limit of sensors that relate physical perturbations to a resonance frequency shift. While the contribution of thermomechanical noise to frequency stability was understood recently, thermal fluctuation noise has attracted less attention despite being the ultimate performance limit of temperature sensing. We provide a model for the frequency stability of NMR considering both additive phase noise (i.e., thermomechanical and detection noises) and thermal fluctuation noise. We then experimentally demonstrate optimized NMR achieving frequency stability limited by thermal fluctuation noise. Our work shows that current models for NMR frequency stability can be incomplete. It also paves a way for NMR radiation detectors to reach the unattained fundamental detectivity limit of thermal-based radiation sensing