Active feedback cooling of a SiN membrane resonator by electrostatic actuation
A. Borrielli (Istituto dei materiali per l'elettronica ed il magnetismo, Consiglio Nazionale delle Ricerche, Fondazione Bruno Kessler, Institute of Materials for Electronics and Magnetism - Nanoscience-Trento-FBK Division)
M. Bonaldi (Istituto dei materiali per l'elettronica ed il magnetismo, Consiglio Nazionale delle Ricerche, Institute of Materials for Electronics and Magnetism - Nanoscience-Trento-FBK Division, Fondazione Bruno Kessler)
E. Serra (Fondazione Bruno Kessler, Istituto dei materiali per l'elettronica ed il magnetismo, Consiglio Nazionale delle Ricerche, Trento Institute for Fundamental Physics and Applications, Institute of Materials for Electronics and Magnetism - Nanoscience-Trento-FBK Division)
P.M. Sarro (TU Delft - Electronic Components, Technology and Materials)
B. Morana (TU Delft - Electronic Components, Technology and Materials, TU Delft - EKL Equipment)
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Abstract
Feedback-based control techniques are useful tools in precision measurements as they allow us to actively shape the mechanical response of high quality factor oscillators used in force detection measurements. In this paper, we implement a feedback technique on a high-stress low-loss SiN membrane resonator, exploiting the charges trapped on the dielectric membrane. A properly delayed feedback force (dissipative feedback) enables the narrowing of the thermomechanical displacement variance in a similar manner to the cooling of the normal mechanical mode down to an effective temperature Teff. In the experiment reported here, we started from room temperature and gradually increasing the feedback gain, we were able to cool down the first normal mode of the resonator to a minimum temperature of about 124mK. This limit is imposed by our experimental setup and, in particular, by the injection of the read-out noise into the feedback. We discuss the implementation details and possible improvements to the technique.