Attonewton-meter torque sensing with a macroscopic optomechanical torsion pendulum
Name
PhysRevA.101.011802.pdf
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663.81 KB
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Adobe PDF
Checksum (MD5)
e83176dcb2583544fe6267d02c393bb2
Author(s)
Sudhir, Vivishek
Date Issued
January 17, 2020
Journal
Physical review. A
Publisher
American Physical Society
Citation
Komori, Kentaro et al. “Attonewton-meter torque sensing with a macroscopic optomechanical torsion pendulum.” Physical review. A 101 (2020): 011802 © 2020 The Author(s)
Version
Final published version
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 tabletop 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 aN m/sqrt[Hz] is a record for a milligram-scale torsional oscillator. This allows us to test spontaneous wave-function collapse in a parameter regime that falls in between that tested by space-based experiments, and high-frequency cryogenic cantilevers.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
MIT Kavli Institute for Astrophysics and Space Research
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1103/PhysRevA.101.011802
