Ultra-stable Cryogenic Nanopositioner for Quantum Optomechanics and Zeptonewton Force Sensing

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The central aim of our research program is to realize ultrasensitive mechanical systems that are actuated and enhanced by laser light. Recently, our group made a major breakthrough, fabricating ~50-nanometer-thin "micro-trampolines" exhibiting world-record force sensitivity at room temperature (with a noise floor measured in attonewtons, or equivalent to the gravitational pull between two people separated by ~100 km). At the same time, these devices achieve extraordinarily low optical losses, making them compatible with the world's most sensitive interferometers for optomechanics experiments. In particular, the demonstrated parameters correspond to a situation in which the forces exerted by light at the level of a single interferometer photon (on average) will profoundly affect the mechanical trajectory. The performance of these and related optomechanical systems will improve by orders of magnitude at cryogenic (millikelvin) temperatures, due to a combination of reduced thermal force noise and increased mechanical quality factor. The resulting unprecedented mechanical coherence will enable a host of exciting optomechanics experiments operating deeply within the regime of macroscopic quantum motion, as well as the development of new quantum information transduction platforms and force sensing at the level of ~10 zeptonewtons, wherein a variety of goals (e.g. nanometer-resolution magnetic resonance imaging) become feasible. Our group already has access to a CFI-funded dilution cryostat, but in order to achieve these extraordinarily sensitive goals, a stable, vibration-isolated, encoded cryogenic nanopositioner is an absolute requirement.