Preliminary Experimental Setup and Baseline Characterization for Detecting Electromagnetic Stress Asymmetry in Asymmetric Resonant Cavities

This work presents the preliminary implementation and baseline characterization of an experimental platform designed to test electromagnetic stress asymmetry in asymmetric resonant cavity systems. Building upon prior theoretical, simulation-based, and protocol-development studies, this paper focuses on instrument stability, calibration, and noise characterization for nanonewton-scale force detection using a torsion balance configuration. Baseline measurements indicate a noise floor in the range of 10–50 nN, consistent with observed time-series fluctuations centered around zero with no persistent directional bias. Repeated measurements confirm the reproducibility of the noise characteristics under identical experimental conditions. No statistically significant force signals are observed under resonant excitation within the current sensitivity threshold. The achieved sensitivity exceeds the predicted force scale by approximately one order of magnitude, providing a clear quantitative benchmark for future improvements. This work establishes a validated experimental baseline and identifies key sources of systematic uncertainty, including thermal drift, vibration, electromagnetic coupling, and electrostatic effects. The results define a practical pathway toward higher-sensitivity measurements, including vacuum operation and enhanced isolation, required to test predicted nanonewton-scale effects.