Search for Millicharged Particles Using Optically Levitated Microspheres

Moore, David C.; Rider, Alexander D.; Gratta, G.

doi:10.1103/physrevlett.113.251801

Cited by 184 publications

(193 citation statements)

References 41 publications

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“…Following demonstrations of ground state cooling in clamped mechanical resonator systems [1][2][3], optical trapping of nanoparticles in vacuum has emerged as a promising technique for pursuing fundamental tests of quantum mechanics [4][5][6][7][8], sensing of weak forces [9][10][11][12], and searches for new physics [13][14][15]. However, the high optical intensities required for trapping can result in excessive heating and trapping instabilities at intermediate vacuum [10,11,16,17].…”

Section: Introductionmentioning

confidence: 99%

Cooling the motion of a silica microsphere in a magneto-gravitational trap in ultra-high vacuum

et al. 2018

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Levitated optomechanical systems, and particularly particles trapped in vacuum, provide unique platforms for studying the mechanical behavior of objects well-isolated from their environment. Ultimately, such systems may enable the study of fundamental questions in quantum mechanics, gravity, and other weak forces. While the optical trapping of nanoparticles has emerged as the prototypical levitated optomechanical system, it is not without problems due to the heating from the high optical intensity required, particularly when combined with a high vacuum environment. Here we investigate a magneto-gravitational trap in ultra-high vacuum. In contrast to optical trapping, we create an entirely passive trap for diamagnetic particles by utilizing the magnetic field generated by permanent magnets and the gravitational interaction. We demonstrate cooling the center of mass motion of a trapped silica microsphere from ambient temperature to an effective temperature near or below one milliKelvin in two degrees of freedom by optical feedback damping.

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Section: Introductionmentioning

confidence: 99%

Cooling the motion of a silica microsphere in a magneto-gravitational trap in ultra-high vacuum

et al. 2018

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“…A levitated nonspherical nanoparticle in vacuum will also be an ultrasensitive nanoscale torsion balance with a torque detection sensitivity on the order of 10 −29 N · m/ √ Hz under realistic conditions. An optically levitated dielectric particle in vacuum [1][2][3] is an ultrasensitive detector for force sensing [4,5], millicharge searching [6] and other applications [7,8]. It will provide a great platform to test fundamental theories such as objective collapse models [9,10] and quantum gravity [11] when its mechanical motion can be cooled to the quantum regime [12,13].…”

mentioning

confidence: 99%

Torsional Optomechanics of a Levitated Nonspherical Nanoparticle

et al. 2016

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An optically levitated nanoparticle in vacuum is a paradigm optomechanical system for sensing and studying macroscopic quantum mechanics. While its center-of-mass motion has been investigated intensively, its torsional vibration has only been studied theoretically in limited cases. Here we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum. We achieve this by utilizing the coupling between the spin angular momentum of photons and the torsional vibration of a nonspherical nanoparticle whose polarizability is a tensor. The torsional vibration frequency can be one order of magnitude higher than its center-of-mass motion frequency, which is promising for ground state cooling. We propose a simple yet novel scheme to achieve ground state cooling of its torsional vibration with a linearly-polarized Gaussian cavity mode. A levitated nonspherical nanoparticle in vacuum will also be an ultrasensitive nanoscale torsion balance with a torque detection sensitivity on the order of 10 −29 N · m/ √ Hz under realistic conditions. An optically levitated dielectric particle in vacuum [1][2][3] is an ultrasensitive detector for force sensing [4,5], millicharge searching [6] and other applications [7,8]. It will provide a great platform to test fundamental theories such as objective collapse models [9, 10] and quantum gravity [11] when its mechanical motion can be cooled to the quantum regime [12,13]. Recently, feedback cooling of the center-of-mass (COM) motion of a levitated nanosphere to about 450 µK (about 63 phonons at 150 kHz) [14], and cavity cooling of the COM motion of a nanosphere to a few mK [15] were demonstrated. The vibration mode would have already been in ground state at 450 µK [14] if its frequency is above 10 MHz. Increasing the vibration frequency of the nanoparticle can be a key to achieve ground state cooling. However, this can not be achieved by simply increasing the intensity of the trapping laser, which induces heating and subsequently causes the loss of the nanoparticle [4,16]. Besides COM motion, a pioneering work has proposed to use multiple Laguerre-Gaussian (LG) cavity modes to achieve angular trapping of a dielectric rod and cool its torsional vibration (TOR) to the ground state [12]. This was later generalized to micro-windmills [17], which have better overlap with LG cavity modes. These intriguing proposals of torsional optomechanics, however, have not been realized experimentally yet.In this work, we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum, and show that the torsional frequency can be one order of magnitude higher than the COM frequency at the same laser intensity. We explain our observation using a model of an ellipsoidal nanoparticle levitated by a linearly-polarized Gaussian beam. For an ellipsoid much smaller than the wavelength of the trapping laser, its polarizability is a tensor due to its geometry [18]. In a linearly polariz...

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“…However, recent experimental work has shown that the charge on optically trapped spheres can be made zero and remain zero for long measurement periods [42,43].…”

Section: Systematicsmentioning

confidence: 99%

Sensing short range forces with a nanosphere matter-wave interferometer

Geraci

Goldman

2015

Phys. Rev. D

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We describe a method for sensing short range forces using matter wave interference in dielectric nanospheres. When compared with atom interferometers, the larger mass of the nanosphere results in reduced wave packet expansion, enabling investigations of forces nearer to surfaces in a freefall interferometer. By laser cooling a nanosphere to the ground state of an optical potential and releasing it by turning off the optical trap, acceleration sensing at the 10 −8 m/s 2 level is possible. The approach can yield improved sensitivity to Yukawa-type deviations from Newtonian gravity at the 5 µm length scale by a factor of 10 4 over current limits.

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Search for Millicharged Particles Using Optically Levitated Microspheres

Cited by 184 publications

References 41 publications

Cooling the motion of a silica microsphere in a magneto-gravitational trap in ultra-high vacuum

Cooling the motion of a silica microsphere in a magneto-gravitational trap in ultra-high vacuum

Torsional Optomechanics of a Levitated Nonspherical Nanoparticle

Sensing short range forces with a nanosphere matter-wave interferometer

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