High sensitivity, levitated microsphere apparatus for short-distance force measurements.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Nanotechnology
• Precision Measurement

Background:

• Optical tweezers are crucial for manipulating microscopic objects.
• High-sensitivity force sensing is essential for nanoscale research and device development.

Purpose of the Study:

• To develop a high-sensitivity force sensor using optically trapped dielectric microspheres in vacuum.
• To enable precise three-dimensional force measurements at short distances.

Main Methods:

• Utilizing a single, upward-propagating laser beam and off-axis parabolic mirrors for optical trapping and position readout.
• Employing an interferometer for vertical degree of freedom measurement and surrounding electrodes for precise electric field control.
• Integrating custom microscopes for real-time metrology within the trapping region.

Main Results:

• Achieved a force noise below 1 × 10⁻¹⁷ N/√Hz on all three degrees of freedom for silica microspheres.
• Demonstrated precise control over microsphere charge state (single electron precision) and mass measurement.
• Successfully positioned devices within 1.6 µm of the trapped microsphere surface without disturbing the optical field.

Conclusions:

• The developed apparatus provides a robust platform for high-sensitivity, three-dimensional force measurements at short ranges.
• This technology opens new avenues for nanoscale force spectroscopy and interaction studies.
• The sensor's precision and control capabilities are suitable for advanced metrology and fundamental physics experiments.