Final Report Summary - IQOS (Integrated Quantum Optomechanical Systems (IQOS))
Experiments in cavity quantum optomechanics rely crucially on the development of high reflectivity and low loss resonators; currently mechanical damping in these structures is the major hurdle for entering the quantum regime with such “macroscopic” systems. In this area IQOS has brought forth significant progress. As outlined above and shown pictorially in the figure below, in the course of this effort we have performed an in-depth study of the design-limited mechanical quality factor, Q, comprising both theoretical and experimental efforts aimed at realizing, for the first time, numerical predictions of support-induced damping, a key loss mechanism in high-quality-factor micro- and nanomechanical resonators [1]. Such studies are vitally important not only for advancing optomechanics experiments, but also for pushing the limits of general micro- and nanomechanical resonators, which have emerged as ubiquitous devices for use in advanced technological applications spanning wireless communications to advanced physical sensors. In order to calculate the design limited Q we have developed an efficient FEM-enabled numerical solver, which employs the recently introduced “phonontunneling” approach [13]. This solver represents a substantial simplification over previous methods, allowing for the investigation of complex geometries, as well as taking into account interference effects between the radiated waves. To experimentally verify the results generated from the solver, we characterize sets of custom fabricated resonators constructed via a novel gas-phase etching technique [14]. The results from these devices show excellent agreement with theoretical predictions; thus, in combination with existing models for other damping channels, our phonon-tunneling solver makes further strides towards a priori prediction of Q in micro- and nanoscale mechanical resonators, enabling computational design of high performance sensors, filters, etc. without the need for prototype development.