Sail membranes for optomechanical accelerometry

Strained membrane resonators have emerged as a promising platform for optomechanical accelerometry; however, the desired combination of low frequency and high Q-mass product requires a rethinking of their dissipation dilution engineering. Applying Bayesian optimization to a Si₃N₄ membrane, we discover a class of sail-like trampoline resonators in which the frequency is decreased by an order of magnitude while preserving the Q-mass product. We demonstrate centimeter-scale sails with kHz frequencies, Qsim10⁷ and Qtimesmasssim 10 g. Vertically integrating a 7 kHz device with a nanoribbon, we realize a monolithic cavity optomechanical accelerometer with a room temperature thermal noise of 40 ng₀/sqrt{Hz}, sufficient to resolve μg₀/sqrt{Hz} ambient vibration over a bandwidth of 4 kHz with a displacement imprecision of 10^-14 m/sqrt{Hz}. Cryogenic arrays of sail membranes may be attractive for new physics searches and distributed quantum sensing experiments.