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, Q∼107 and Q×mass∼ 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 40ng0/Hz, sufficient to resolve μg0/Hz ambient vibration over a bandwidth of 4 kHz with a displacement imprecision of 10−14m/Hz. Cryogenic arrays of sail membranes may be attractive for new physics searches and distributed quantum sensing experiments.
Testing the limits of the applicability of quantum mechanics will deepen our understanding of the universe and may shed light on the interplay between quantum mechanics and gravity. At present there is a wide range of approaches for such macroscopic tests spanning from matter-wave interferometry of large molecules to precision measurements of heating rates in the motion of micro-scale cantilevers. The “displacemon” is a proposed electromechanical device consisting of a mechanical resonator flux-coupled to a superconducting qubit enabling generation and readout of mechanical quantum states. In the original proposal, the mechanical resonator was a carbon nanotube, containing 106 nucleons. Here, in order to probe quantum mechanics at a more macroscopic scale, we propose using an aluminum mechanical resonator on two larger mass scales, one inspired by the Marshall–Simon–Penrose–Bouwmeester moving-mirror proposal, and one set by the Planck mass. For such a device, we examine the experimental requirements needed to perform a more macroscopic quantum test and thus feasibly detect the decoherence effects predicted by two objective collapse models: Diósi–Penrose and continuous spontaneous localization. Our protocol for testing these two theories takes advantage of the displacemon architecture to create non-Gaussian mechanical states out of equilibrium with their environment and then analyzes the measurement statistics of a superconducting qubit. We find that with improvements to the fabrication and vibration sensitivities of these electromechanical devices, the displacemon device provides a new route to feasibly test decoherence mechanisms beyond standard quantum theory.