Work

Dynamics of microparticle launching and loading into optical traps

Year: 2025

Type: article

Abstract: Levitated optomechanics is opening new opportunities for quantum measurement in mesoscopic systems and for understanding the transition between quantum and classical mechanics. But loading microparticles into optical traps for measurements in vacuum remains an obstacle to the development of the field, in part because the process of launching particles so that they can be efficiently trapped remains poorly understood. We measure the dynamics of particle motion from vibrational excitation and launch from a surface to trapping in air. We demonstrate the direction of launch from a resonantly vibrating glass coverslip to be highly anisotropic and the measured escape velocity of tens to hundreds of millimeters per second to be insensitive to the amplitude of vibrational excitation. For a single particle launched repeatedly, escape velocities less than 50 mm per second are trapped with the highest probability. Trajectories from the launch point to the trap are found to follow a roughly two-step process in air: rapid deceleration due to drag, followed by drift into the trapping region that is accurately modeled by the Stokes-Einstein relation. These results illuminate the launch process in air, supporting the development of controlled launching of microparticles to enable application in a vacuum. This also enables selecting particles for trapping to optimize characteristics such as shape or Mie spectra, as well as repeated measurement of single particles to ensure reproducibility.

Source: Optics Express

DOI: 10.1364/oe.572111

Authors: Kwan Seob Park, Kiana Malmir, Glenn E. Holland, Martin Y. Sohn, Thomas W. LeBrun

Language: English

Topic: Orbital Angular Momentum in Optics

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270

Funder: National Institute of Standards and Technology

Award: PURPOSE:THE PURPOSE OF THIS GRANT IS TO DEVELOP AN INSTRUMENT TO LEVITATE MICROPARTICLES IN VACUUM AND TO USE THE INSTRUMENT TO INVESTIGATE APPROACHES TO CONTROLLING THE QUANTUM STATE OF LEVITATED PARTICLES. ACTIVITIES TO BE PERFORMED:A VACUUM CHAMBER AND INSTRUMENTATION WILL BE DEVELOPED TO LAUNCH MICROPARTICLES AND TRAP THEM IN VACUUM USING A LASER AT 1064 NM WAVELENGTH. THE CAPACITY TO MEASURE THE PARTICLE MOTION WILL BE INCLUDED BY ADDING A LASER BEAM AT VISIBLE WAVELENGTH (633 NM) WITH MULTIPLE DETECTORS TO MONITOR THE BEAM TRANSMITTED BY THE PARTICLE. THE OPTICAL SPECTRA OF THE PARTICLES WILL BE MEASURED USING A THIRD BEAM WITH A WAVELENGTH TUNABLE BETWEEN 1530 AND 1630 TO MONITOR THE SCATTERING. THE WAVELENGTHS OF LOW LOSS (HIGH-Q) RESONANCES IN THE OPTICAL SPECTRA WILL BE DETERMINED AND THE RESONANCES IDENTIFIED BY COMPARISON TO CALCULATIONS FROM MIE THEORY. THE VIBRATIONAL SPECTRA OF THE PARTICLES WILL BE MEASURED BY RECORDING THEIR SIGNATURE IN THE OPTICAL SPECTRA. VIBRATIONAL SPECTRA WILL BE RECORDED UNDER VARYING CONDITIONS TO DETERMINE THE EFFICACY OF CONTROL OF THE VIBRATIONAL STATE BY MODULATING THE OPTICAL BEAMS? INTERACTION WITH THE PARTICLE. EXPECTED OUTCOMES:THIS WORK WILL PROVIDE A FACILITY TO PRODUCE HIGHLY ISOLATED MICROPARTICLES BY VACUUM LEVITATION. IT WILL ALSO CREATE A PLATFORM TO STUDY QUANTUM CONTROL IN A RANGE OF NEW SYSTEMS, INCLUDING LARGER SYSTEMS THAN HAS BEEN PREVIOUSLY ACHIEVED, VIBRATION IN LEVITATED SYSTEMS, AND ROTATION FOR INERTIAL MEASUREMENT. INTENDED BENEFICIARIES:THE US WILL BENEFIT BY DEVELOPING NEW CAPABILITIES IN CRITICAL AND EMERGING AREAS, INCLUDING QUANTUM SENSING AND RESILIENT POSITIONING, NAVIGATION, AND TIMING. SUBRECIPIENT ACTIVITIES: THE RECIPIENT DOES NOT INTEND TO SUBAWARD FUNDS.