Stronger limits on hypothetical Yukawa interactions in the 40--8000 nm range

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We report the results of new differential force measurements between a test mass and rotating source masses of gold and silicon to search for forces beyond Newtonian gravity at short separations.

• The technique employed subtracts the otherwise dominant Casimir force at the outset and, when combined with a lock-in amplification technique, leads to a significant improvement (up to a factor $10^{3}$) over existing limits on the strength (relative to gravity) of a putative force in the 40--8000 nm interaction range.