Precision Mass and Density Measurement of Individual Optically Levitated Microspheres

Blakemore, Charles P.; Rider, Alexander D.; Roy, Sujata; Fieguth, A.; Kawasaki, Akio; Priel, N.; Gratta, G.

doi:10.1103/physrevapplied.12.024037

Cited by 37 publications

(20 citation statements)

References 37 publications

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“…The values of κ determined with these analyses are shown in Table II, together with the individual MS radii and the expected value of κ, which have both been computed from the known value of the density [33] and the measured value of the MS mass, assuming the MS is thermal equilibrium with the gas. The consistency between the measured and calculated values suggest that in moderate vacuum, P ≈ 10 −3 − 10 −1 mbar, the MS is indeed in thermal equilibrium with the gas.…”

Section: Capacitance Manometer Cross-checkmentioning

confidence: 99%

Absolute pressure and gas species identification with an optically levitated rotor

Blakemore

Martin

Fieguth

et al. 2020

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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We describe a novel variety of spinning-rotor vacuum gauge in which the rotor is a ∼4.7-µmdiameter silica microsphere, optically levitated. A rotating electrostatic field is used to apply torque to the permanent electric dipole moment of the silica microsphere and control its rotational degrees of freedom. When released from a driving field, the microsphere's angular velocity decays exponentially with a damping time inversely proportional to the residual gas pressure, and dependent on gas composition. The gauge is calibrated by measuring the rotor mass with electrostatic co-levitation, and assuming a spherical shape, confirmed separately, and uniform density. The gauge is crosschecked against a capacitance manometer by observing the torsional drag due to a number of different gas species. The techniques presented can be used to perform absolute vacuum measurements localized in space, owing to the small dimensions of the microsphere, as well as measurements in magnetic field environments. In addition, the dynamics of the microsphere, paired with a calibrated vacuum gauge, can be used to measure the effective molecular mass of a gas mixture without the need for ionization, and at pressures up to approximately 1 mbar.

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Section: Capacitance Manometer Cross-checkmentioning

confidence: 99%

Absolute pressure and gas species identification with an optically levitated rotor

Blakemore

Martin

Fieguth

et al. 2020

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

Self Cite

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“…Technical noise is a particular obstacle for torque sensing with fast nanorotors because it linearly increases with rotational frequency and makes shot-noise-limited operation difficult [91]. Other challenges include calibration uncertainties (e.g., particle mass) [116,[181][182][183] and the temperature dependence of system parameters (e.g., index of refraction of particle). Although some of these noise sources can be suppressed by differential measurements, the potential of levitation-based sensors for commercial applications requires thorough evaluation and optimization procedures.…”

Section: Open Challengesmentioning

confidence: 99%

Levitodynamics: Levitation and control of microscopic objects in vacuum

Gonzalez-Ballestero,

Aspelmeyer,

Novotny

et al. 2021

Preprint

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The control of levitated nano-and micro-objects in vacuum is of considerable interest, capitalizing on the scientific achievements in the fields of atomic physics, control theory and optomechanics. The ability to couple the motion of levitated systems to internal degrees of freedom, as well as to external forces and systems, provides opportunities for science and technology. Attractive research directions, ranging from fundamental quantum physics to commercial sensors, have been unlocked by the many recent experimental achievements, including motional ground-state cooling of an optically levitated nanoparticle. We review the status, challenges and prospects of levitodynamics, the mutidisciplinary research devoted to understanding, controlling, and using levitated nano-and micro-objects in vacuum.

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“…Two independent methods were recently employed to measure the refractive index of silica microspheres from the same batch at λ 0 = 470 nm [84]. The result is smaller than the bulk fused silica index, which we attribute to the porosity of the beads (see also [131] for related findings from a mass measurement). In order to infer the refractive index at the trapping laser wavelength λ 0 = 1064 nm, we employ the (Mie-based) extended Maxwell-Garnett (EMG) effective medium theory [132,133] assuming that our silica beads are filled with empty pores.…”

Section: Trap Stiffness Calibrationmentioning

confidence: 99%

Probing the screening of the Casimir interaction with optical tweezers

Pires,

Ether,

Spreng

et al. 2021

Preprint

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We measure the colloidal interaction between two silica microspheres in aqueous solution in the distance range from 0.2 µm to 0.5 µm with the help of optical tweezers. When employing a sample with a low salt concentration, the resulting interaction is dominated by the repulsive double-layer interaction which is fully characterized. The double-layer interaction is suppressed when adding 0.22 M of salt to our sample, thus leading to a purely attractive Casimir signal. When analyzing the experimental data for the potential energy and force, we find good agreement with theoretical results based on the scattering approach. At the distance range probed experimentally, the interaction arises mainly from the unscreened transverse magnetic contribution in the zero-frequency limit, with nonzero Matsubara frequencies providing a negligible contribution. In contrast, such unscreened contribution is not included by the standard theoretical model of the Casimir interaction in electrolyte solutions, in which the zero-frequency term is treated separately as an electrostatic fluctuational effect. As a consequence, the resulting attraction is too weak in this standard model, by approximately one order of magnitude, to explain the experimental data. Overall, our experimental results shed light on the nature of the thermal zero-frequency contribution and indicate that the Casimir attraction across polar liquids has a longer range than previously predicted.

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Precision Mass and Density Measurement of Individual Optically Levitated Microspheres

Cited by 37 publications

References 37 publications

Absolute pressure and gas species identification with an optically levitated rotor

Absolute pressure and gas species identification with an optically levitated rotor

Levitodynamics: Levitation and control of microscopic objects in vacuum

Probing the screening of the Casimir interaction with optical tweezers

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