Search for Screened Interactions Associated with Dark Energy below the 100 μm Length Scale.

Area of Science:

• Experimental physics
• Fundamental forces
• Gravitational physics

Background:

• Searches for new fundamental forces are crucial for understanding physics beyond the Standard Model.
• Previous experiments were limited by screening mechanisms, hindering the detection of forces at micrometer scales.
• Optically levitated microspheres offer a unique platform for probing new interactions due to their isolation and controllability.

Purpose of the Study:

• To search for unknown interactions coupling to mass at sub-100 micrometer distances.
• To place experimental constraints on new forces that may have evaded previous detection.
• To test specific models of new physics, such as chameleon interactions.

Main Methods:

• Utilizing an optically levitated microsphere interacting with a gold-coated silicon cantilever.
• Designing an apparatus with specific geometry to probe short-range forces below 100 micrometers.
• Analyzing data for deviations from known forces, particularly electrostatic backgrounds.

Main Results:

• Experimental data were consistent with expected electrostatic backgrounds.
• Upper limits on the strength of new interactions were established at less than 0.1 femtonewtons (fN).
• Specific chameleon interaction models with inverse power-law potentials were excluded for matter couplings β > 5.6×10⁴.

Conclusions:

• The experiment successfully constrained new, short-range forces coupling to mass.
• The findings exclude a significant parameter space for chameleon interactions, particularly where self-coupling is high and screening is minimal.
• This work demonstrates the potential of levitated optomechanical systems for fundamental physics searches.