2008/11/09 by Jack C. Sankey, Sankey, Jack C., Andrew M. Jayich +7
Engineering · Physics and Astronomy · #Advanced MEMS and NEMS Technologies #FOS: Physical sciences #Force Microscopy Techniques and Applications #Mechanical and Optical Resonators #Quantum Physics (quant-ph)
paper · pdf · doi:10.48550/arxiv.0811.1343
openalex publication_date 2008/11/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Optomechanical devices in which a flexible SiN membrane is placed inside an optical cavity allow for very high finesse and mechanical quality factor in a single device. They also provide fundamentally new functionality: the cavity detuning can be a quadratic function of membrane position. This enables a measurement of "position squared" (x2) and in principle a QND phonon number readout of the membrane. However, the readout achieved using a single transverse cavity mode is not sensitive enough to observe quantum jumps between phonon Fock states. Here we demonstrate an x2-sensitivity that is orders of magnitude stronger using two transverse cavity modes that are nearly degenerate. We derive a first-order perturbation theory to describe the interactions between nearly-degenerate cavity modes and achieve good agreement with our measurements using realistic parameters. We also demonstrate theoretically that the x2-coupling should be easily tunable over a wide range.