Atto-Nm Torque Sensing with a Macroscopic Optomechanical Torsion Pendulum

Abstract

Precise measurements of the displacement of, and force acting on, a mechanical oscillator can be performed by coupling the oscillator to an optical cavity. Brownian thermal forces represent a fundamental limit to measurement sensitivity which impedes the ability to use precise force measurements as a tool of fundamental enquiry, particularly in the context of macroscopic quantum measurements and table-top gravitational experiments. A torsion pendulum with a low mechanical resonant frequency can be limited by very small thermal forces - from its suspensions - at frequencies above resonance. Here, we report torque sensing of a 10-mg torsion pendulum formed by a bar mirror, using two optical cavities on either edge. The rotational mode was measured by subtracting the two signals from the cavities, while intracavity radiation pressure forces were used to trap the torsional mode with a 1 kHz optical spring. The resulting torque sensitivity of 20 aNm/$\sqrt{\mathrm{Hz}}$ is a record for a milligram scale torsion pendulum. Such a massive optomechanical device featuring high sensitivity can shed light on macroscopic quantum mechanics and gravitational physics.

arXiv comment5 pages, 3 figures

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Cited by in corpus (23)

• Narrowing the parameter space of collapse models with ultracold layered force sensors
• Observation of radiation torque shot noise on an optically levitated nanodumbbell
• High Q mg-scale monolithic pendulum for quantum-limited gravity measurements
• Mechanical dissipation below 1$\mu$Hz with a cryogenic diamagnetic-levitated micro-oscillator
• Quantum sensing with milligram scale optomechanical systems
• Testing the quantum nature of gravity without entanglement
• Radiation pressure measurement using a macroscopic oscillator in an ambient environment
• Perspectives of measuring gravitational effects of laser light and particle beams
• Macroscopic quantum entanglement between an optomechanical cavity and a continuous field in presence of non-Markovian noise
• Quantum-limited optical lever measurement of a torsion oscillator
• Angular trapping of a linear-cavity mirror with an optical torsional spring
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• Improving force sensitivity by amplitude measurement of light reflected from a detuned optomechanical cavity
• Cavity Optomechanical Probe of Gravity Between Massive Mechanical Oscillators
• Random non-Hermitian action theory for stochastic quantum dynamics: from canonical to path integral quantization
• First result for testing semiclassical gravity effect with a torsion balance
• Random non-Hermitian Hamiltonian framework for symmetry breaking dynamics
• Cross-Correlated Force Measurement for Thermal Noise Reduction in Torsion Pendulum
• Testing Continuous Spontaneous Localization model with charged macro-molecules
• Measuring optical force with a torsion pendulum: a platform for independent student experimentation
• Measurement-based preparation of non-Markovian and multimode mechanical states
• Statistical Symmetry Breaking and Emergent Colored Noise in a Stochastic Scalar-Doublet Field Theory
• Testing the weak equivalence principle for nonclassical matter with torsion balances