Transverse spin forces and non-equilibrium particle dynamics in a circularly polarized vacuum optical trap

Svak, Vojtěch; Brzobohatý, Oto; Šiler, Martin; Jákl, Petr; Kaňka, Jan; Zemánek, Pavel; Simpson, Stephen H.

doi:10.1038/s41467-018-07866-8

Cited by 81 publications

(84 citation statements)

References 33 publications

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“…This is a nonequilibrium effect, and the motional energy greatly exceeds the thermal energy, 1 _ 2 k B T . The effect is loosely analogous to that previously reported for isotropic spheres in circularly polarized beams (23), except that, in this case, the nonconservative motion is induced by particle anisotropy rather than by momentum flows within the trapping beam. Since the optical forces experienced by a particle depend qualitatively on its shape (24)(25)(26)(27), a range of exotic behaviors may be anticipated for particles of yet lower symmetry.…”

Section: Discussionsupporting

confidence: 83%

Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling

et al. 2020

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We demonstrate an effect whereby stochastic, thermal fluctuations combine with nonconservative optical forces to break detailed balance and produce increasingly coherent, apparently deterministic motion for a vacuum-trapped particle. The particle is birefringent and held in a linearly polarized Gaussian optical trap. It undergoes oscillations that grow rapidly in amplitude as the air pressure is reduced, seemingly in contradiction to the equipartition of energy. This behavior is reproduced in direct simulations and captured in a simplified analytical model, showing that the underlying mechanism involves nonsymmetric coupling between rotational and translational degrees of freedom. When parametrically driven, these self-sustained oscillators exhibit an ultranarrow linewidth of 2.2 μHz and an ultrahigh mechanical quality factor in excess of 2 × 108 at room temperature. Last, nonequilibrium motion is seen to be a generic feature of optical vacuum traps, arising for any system with symmetry lower than that of a perfect isotropic microsphere in a Gaussian trap.

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Section: Discussionsupporting

confidence: 83%

Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling

et al. 2020

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“…• Vacuum levitation Recent progress in optomechanics [567], especially in the levitation of objects optically confined in vacuum [568], promises a fundamental quantitative increase in the detection sensitivity of ultraweak forces [569][570][571] and torques [572][573][574], opening of new paths to experimental realization of microscopic stochastic systems that are far from equilibrium and whose phase space can be fully externally controlled [575,576], as well as a qualitative technological push towards quantum technologies based on optically cooled center-of-mass motion of levitated nanoobjects [258,303,571,[577][578][579][580][581][582]. Downsizing the experimental platforms from conventional bulky vacuum chambers to vacuum chips represents a critical step towards their practical utilization [304,583].…”

Section: Discussionmentioning

confidence: 99%

Perspective on light-induced transport of particles: from optical forces to phoretic motion

et al. 2019

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Propulsive effects of light, which often remain unnoticed in our daily-life experience, manifest themselves on spatial scales ranging from subatomic to astronomical. Light-mediated forces can indeed confine individual atoms, cooling their effective temperature very close to absolute zero, as well as contribute to cosmological phenomena such as the formation of stellar planetary systems. In this review, we focus on the transport processes that light can initiate on small spatial scales. In particular, we discuss in depth various light-induced mechanisms for the controlled transport of microscopic particles; these mechanisms rely on the direct transfer of momentum between the particles and the incident light waves, on the combination of optical forces with external forces of other nature, and on light-triggered phoretic motion. After a concise theoretical overview of the physical origins of optical forces, we describe how these forces can be harnessed to guide particles either in continuous bulk media or in the proximity of a constraining interface under various configurations of the illuminating light beams (radiative, evanescent, or plasmonics fields). Subsequently, we introduce particle transport techniques that complement optical forces with counteracting forces of non-optical nature. We finally discuss particle actuation schemes where light acts as a fine knob to trigger and/or modulate phoretic motion in spatial gradients of non-optical (e.g., electric, chemical, or temperature) fields. We conclude by outlining possible future fundamental and applied directions for research in light-induced particle transport. We believe that this comprehensive review can inspire diverse, interdisciplinary scientific communities to devise novel, unorthodox ways of assembling and manipulating materials with light.

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“…Unstructured, plane-wave-like light fields can induce optical lateral forces on appropriately shaped objects as an optical analogue to aerodynamic lift 14 . Circularly polarized (CP) beams can induce spin-dependent lateral forces on achiral spherical particles when they are placed near an interface 15,16 . The displacements of particles controlled by the spin of the light can be perpendicular to the direction of the light beam [17][18][19] .…”

Section: Introductionmentioning

confidence: 99%

Chirality-assisted lateral momentum transfer for bidirectional enantioselective separation

et al. 2020

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Lateral optical forces induced by linearly polarized laser beams have been predicted to deflect dipolar particles with opposite chiralities toward opposite transversal directions. These "chirality-dependent" forces can offer new possibilities for passive all-optical enantioselective sorting of chiral particles, which is essential to the nanoscience and drug industries. However, previous chiral sorting experiments focused on large particles with diameters in the geometrical-optics regime. Here, we demonstrate, for the first time, the robust sorting of Mie (size~wavelength) chiral particles with different handedness at an air-water interface using optical lateral forces induced by a single linearly polarized laser beam. The nontrivial physical interactions underlying these chirality-dependent forces distinctly differ from those predicted for dipolar or geometrical-optics particles. The lateral forces emerge from a complex interplay between the light polarization, lateral momentum enhancement, and out-of-plane light refraction at the particle-water interface. The sign of the lateral force could be reversed by changing the particle size, incident angle, and polarization of the obliquely incident light.

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Transverse spin forces and non-equilibrium particle dynamics in a circularly polarized vacuum optical trap

Cited by 81 publications

References 33 publications

Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling

Coherent oscillations of a levitated birefringent microsphere in vacuum driven by nonconservative rotation-translation coupling

Perspective on light-induced transport of particles: from optical forces to phoretic motion

Chirality-assisted lateral momentum transfer for bidirectional enantioselective separation

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