Optically levitated nanoparticles offer enormous potential for precision sensing. However, as for any other metrology device, the absolute measurement performance of a levitated-particle sensor is limited by the accuracy of the calibration relating the measured signal to an absolute displacement of the particle. Here, we suggest and demonstrate calibration protocols for levitated-nanoparticle sensors. Our calibration procedures include the treatment of anharmonicities in the trapping potential, as well as a protocol using a harmonic driving force, which is applicable if the sensor is coupled to a heat bath of unknown temperature. Finally, using the calibration, we determine the center-of-mass temperature of an optically levitated particle in thermal equilibrium from its motion, and discuss the optimal measurement time required to determine said temperature.
@article{arxiv.1711.09049,
title = {Calibration and temperature measurement of levitated optomechanical sensors},
author = {Erik Hebestreit and Martin Frimmer and René Reimann and Christoph Dellago and Francesco Ricci and Lukas Novotny},
journal= {arXiv preprint arXiv:1711.09049},
year = {2018}
}