Seismic nonlinear coupling noise is one of the limiting factors for high-accuracy torsion pendulums. Based on the common-mode rejection of dual torsion pendulums, a seismic coupling noise suppression approach is proposed and verified by modulation experiments. By mounting two nearly identical pendulums on a single frame within a vacuum chamber, seismic disturbances on the torque noise act as common-mode signals that can be effectively canceled. Modulation experiments are performed to evaluate the common-mode rejection (CMR) performance. Modulation results demonstrate that, by applying the driven vibration, the raw noise of the pendulum increases to $1.4\times {10}^{-14}\text{Nm}/{\mathrm{Hz}}^{1/2}$ at around 2 mHz, while the CMR-processed noise stays at $1.1\times {10}^{-15}\text{Nm}/{\mathrm{Hz}}^{1/2}$, which confirms a CMR noise suppression of over one order of magnitude. This validates a practical approach for improving the torsional pendulum accuracy in small-force scientific measurements.

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• Classical mechanics
• Gravitation
• Interactions & forces
• Laboratory studies of gravity
• Metrology
• Noise
• Rotation sensing
• Precision measurements