Silicon-nitride nanosensors toward room temperature quantum optomechanics

Observation of quantum phenomena in cryogenic, optically cooled mechanical resonators has been recently achieved by a few experiments based on cavity optomechanics. A well-established experimental platform is thin film stoichiometric ($ Si_3 N_4 $) nanomembrane embedded Fabry-Perot cavity, where the coupling with light field provided radiation pressure impinging membrane surface. Two crucial parameters have to be optimized ensure that these systems work at level: cooperativity $ C$ describing optomechanical and product Q \times \nu$ (quality factor - resonance frequency) related decoherence rate. significant increase latter can obtained high aspect-ratio uniform stress dilutes dissipation. Furthermore, ultra-high $Q reached drastically reducing edge dissipation via clamp-tapering and/or soft-clamping, virtually clamp-free resonator configuration. In this work, we investigate, theoretically experimentally, loss mechanisms comparing two state-of-the-art built standard micro/nanofabrication techniques. The corresponding results would provide meaningful guidelines for designing new ultra-coherent resonating devices.