Nanofabricated torsion pendulums for tabletop gravity experiments

TL;DR

This paper presents a nanofabricated torsion pendulum with a large test mass, offering a promising platform for precise tabletop experiments to measure gravitational interactions at small scales.

Contribution

It demonstrates the largest silicon nitride-based torsion oscillator to date, enabling improved sensitivity for gravity experiments using nanofabricated suspensions.

Findings

Achieved a 87-gram test mass with a 250 micron by 5 mm by 1.8 micron torsion fiber.

Demonstrated the potential for high-quality factors through material loss dilution.

Provides a new experimental platform for probing classical and quantum gravity at small scales.

Abstract

Measurement of mutual gravitation on laboratory scales is an outstanding challenge and a prerequisite to probing theories of quantum gravity. A leading technology in tabletop gravity experiments is the torsion balance, with limitations due to thermal decoherence. Recent demonstrations of lithographically defined suspensions in thin-film silicon nitride with macroscale test masses suggest a path forward, as torsion pendulums dominated by gravitational stiffness may achieve higher mechanical quality factors through dilution of material losses. Here we demonstrate a 250 micron by 5 mm by 1.8 micron torsion fiber supporting 87 grams and forming a Cavendish-style torsion pendulum with tungsten test masses that -- to our knowledge -- is the largest thin-film silicon-nitride-based oscillator to date. Torsion pendulums with thin-film, nanofabricated suspensions provide a test bed for near-term tabletop experiments probing classical and quantum gravitational interaction between oscillators.