Force Detection Sensitivity Spectrum Calibration of Levitated Nanomechanical Sensor Using Harmonic Coulomb Force

TL;DR

This paper introduces a calibration method for levitated nanomechanical sensors using harmonic Coulomb force, enabling spectral sensitivity characterization beyond thermal noise limits for high-precision force detection.

Contribution

The study presents a novel calibration technique based on harmonic Coulomb force to accurately measure the spectral force detection sensitivity of levitated sensors.

Findings

Achieved a thermal noise limit sensitivity of (4.39 ± 0.62) × 10^{-20} N/Hz^{1/2} at 2.4×10^{-6} mbar

Measured sensitivity away from resonance was around 10^{-17} N/Hz^{1/2}

Calibration method applicable to various optical levitation systems

Abstract

Oscillators based on levitated particles are promising for the development of ultrasensitive force detectors. The theoretical performance of levitated nanomechanical sensors is usually characterized by the so-called thermal noise limit force detection sensitivity, which does not exhibit spectral specificity in practical measurements. To characterize the actual detection performance, we propose a method for the force detection sensitivity calibration of a levitated nanomechanical sensor based on the harmonic Coulomb force. Utilizing the measured transfer function, we obtained the force detection sensitivity spectrum from the position spectrum. Although the thermal noise limit force detection sensitivity of the system reached $\rm\left( {4.39 \pm 0.62} \right) \times {10^{ - 20}} N/H{z^{1/2}}$ at $\rm{2.4\times10^{-6} mbar}$ with feedback cooling, the measured sensitivity away from the resonance was of the order of $\rm10^{-17} N/Hz^{1/2}$ based on the existing detection noise level. The calibration method established in our study is applicable to the performance evaluation of any optical levitation system for high-sensitivity force measurements.