Nano-optomechanical systems: sense and sense-stability

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A recent breakthrough [Roy, Sauer, Westwood-Bachman, Venkatasubramanian, Hiebert (2018) Science 360, eaar5220] showed the unexpected result that precision mechanical resonator performance can be improved by reducing quality factor (increasing damping). This has profound implications for future development in oscillator clocks and resonant sensors. In particular, precision resonators and oscillators are no longer limited to operation in vacuum, but could be potentially enhanced by operation in a viscous damping environment (such as air).*******This program will explore impact avenues from this new paradigm viewpoint of mechanical sensing and stability called the flatband regime. My long term vision is the enablement of sophisticated, ubiquitous, super sensors such as hand-held mass-spectrometers of breath. Short-term objectives of the program will take advantage of the paradigm in the following themes.******1) Improving stability in non-contact atomic force microscopy (AFM) ***We can immediately apply the flatband model for improved stability, force sensitivity, and speed of measurement in frequency modulated AFM. Atomic resolution AFM in situ during chemical reactions is one important frontier that could be greatly impacted by this objective.*******2) Testing the stability model for optomechanics and self-oscillation****We seek to explore the interplay of the physics of feedback loop models with the rich variety of signal control available from the nano-optomechanical systems toolbox. The latter systems provide a wealth of coupling and back-action forces and phases that can be tuned. The new flatband stability model in our above science paper implies that standard components of oscillator phase noise (e.g. Leeson effect) may be mitigated through choice of phase-locked loop parameters. If possible, this could lead to breakthroughs not just in stability of AFM, cantilever sensors, and clock oscillators, but in control theory generally.*******3) Demonstrating air-flow self-oscillation at the nanoscale****Finally, we will take advantage of our newfound high-damping stability regime to explore nanomechanical oscillator physics using air streams as a DC energy source (like a harmonica). Starting from existing nano-optomechanical platforms, a constant air-stream flow across a chip surface is anticipated to excite nanoscale cantilevers into self-oscillation due to flow instabilities. The resulting technology could provide a simple, robust mechanism for driving large arrays of nanoscale oscillators for clock or sensor array applications, such as nanoscale mass spectrometry.***