Casimir force measurements in Au-Au and Au-Si cavities at low temperature

TL;DR

This study measures the Casimir force between gold and silicon surfaces at low temperatures using a cryogenic microscope, highlighting the impact of electrostatic environment and material properties on the force.

Contribution

It provides new experimental data on Casimir forces in Au-Au and Au-Si cavities at cryogenic temperatures, emphasizing the role of electrostatic effects and calibration accuracy.

Findings

Electrostatic environment significantly affects weak force measurements.

Casimir force measurements agree with theory at short distances after minimizing parasitic forces.

Material dielectric properties influence the measured Casimir force.

Abstract

We report on measurements of the Casimir force in a sphere-plane geometry using a cryogenic force microscope to move the force probe in situ over different materials. We show how the electrostatic environment of the interacting surfaces plays an important role in weak force measurements and can overcome the Casimir force at large distance. After minimizing these parasitic forces, we measure the Casimir force between a gold-coated sphere and either a gold-coated or a heavily doped silicon surface in the 100-400 nm distance range. We compare the experimental data with theoretical predictions and discuss the consequence of a systematic error in the scanner calibration on the agreement between experiment and theory. The relative force over the two surfaces compares favorably with theory at short distance, showing that this Casimir force experiment is sensitive to the dielectric properties of the interacting surfaces.