Probing gravity at megahertz frequencies with levitated rotors

Abstract:The near-field gravitational interaction between masses is always thought of as instantaneous, an assumption experimentally tested only up to 1.7 kHz, where measurements yield a bounds at the $10^{-5}$ s level. We propose a near-field experiment reaching up to megahertz frequencies, in which a levitated microrotor modulates a mass quadrupole and a second rotor measures the resulting gravitational tidal field as a torque. Because the detector rotor acts as a mechanical local oscillator, the megahertz signal is downconverted to a convenient band of a few hertz, and since at fixed geometry neither the torque nor the integration time depends on the rotation rate, higher frequencies are reached at no cost in sensitivity. With parameters within reach of magnetically levitated NdFeB rotors, a signal at 2 MHz yields a torque of $2\cdot 10^{-25}$ Nm, detectable in under an hour at 10 mK. Treating a possible departure from instantaneous gravitational coupling through a field relaxation time, the measured torque could constrain it at the $10^{-8}$ s level, improving on the existing bounds by more than three orders of magnitude. As a byproduct of our analysis, we derive the sensitivity of a rotor operated as a tunable high-frequency gravitational-wave detector, finding that a noise-equivalent strain around $10^{-22}$ Hz$^{-1/2}$ could be achievable in the megahertz band.

arXiv:2611.06893 [quant-ph]

(or arXiv:2611.06893v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2611.06893 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs.