Speaker: Aaron Markovitz, Caltech

Title: Precision Sensing with Optomechanically Nonlinear Mach-Zehnder Interferometers

Abstract: In optomechanical devices, the Kerr-like radiation pressure interaction leads to both measurement backaction noise and signal amplification. We are developing an optomechanical preamplifier for quantum squeezed, photodetection loss limited sensors like next generation LIGO facilities. The preamplifier is based on a Mach-Zehnder interferometer with resonant traveling-wave cavities in each arm. Our prototype’s 1550 nm pump laser provides forward bias driving the cavity’s gram-scale mirrors, which are suspended at ~10s Hz by silicon cantilevers. The Mach-Zehnder interferometer’s common mode noise rejection will reduce input-referred amplifier noises below vacuum photon shot noise. We also show how a more general, recycled Mach-Zehnder interferometer could realize several desirable features, including a novel optical spring mechanism with no detuning or membrane-in-the-middle. The “double-pass optical spring” avoids the tradeoff between linewidth and rigidity facing diverse experiments with detuned resonance optical springs.