Detecting Casimir torque with an optically levitated nanorod

Xu, Zhujing; Li, Tongcang

doi:10.1103/physreva.96.033843

Cited by 76 publications

(64 citation statements)

References 59 publications

(95 reference statements)

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“…A levitated nanodumbbell has achieved an unprecedented torque sensitivity of 4 × 10 −27 Nm/ √ Hz [14]. Levitated nonspherical particles have also been proposed to measure the Casimir torque [37], create rotational matter-wave interferometers [38], and search for high-frequency gravitational waves [39].…”

Section: Introductionmentioning

confidence: 99%

Five-dimensional cooling and nonlinear dynamics of an optically levitated nanodumbbell

Bang

Seberson

et al. 2020

Phys. Rev. Research

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Optically levitated nonspherical particles in vacuum are excellent candidates for torque sensing, rotational quantum mechanics, high-frequency gravitational wave detection, and multiple other applications. Many potential applications, such as detecting the Casimir torque near a birefringent surface, require simultaneous cooling of both the center-of-mass motion and the torsional vibration (or rotation) of a nonspherical nanoparticle. Here we report five-dimensional cooling of a levitated nanoparticle. We cool the three center-of-mass motion modes and two torsional vibration modes of a levitated nanodumbbell in a linearly polarized laser simultaneously. The only uncooled rigid-body degree of freedom is the rotation of the nanodumbbell around its long axis. This free rotation mode does not couple to the optical tweezers directly. Surprisingly, we observe that it strongly affects the torsional vibrations of the nanodumbbell. This work deepens our understanding of the nonlinear dynamics and rotation coupling of a levitated nanoparticle and paves the way towards full quantum control of its motion.

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Section: Introductionmentioning

confidence: 99%

Five-dimensional cooling and nonlinear dynamics of an optically levitated nanodumbbell

Bang

Seberson

et al. 2020

Phys. Rev. Research

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“…A levitated nanoparticle has been used to study nonequilibrium thermodynamics at small scales [24][25][26][27] and demonstrate force sensing at the zeptonewton scale [13]. It was proposed that an optically levitated nonspherical nanoparticle in vacuum would be an ultrasensitive torque sensor [22] and could study anisotropic surface interactions [28]. While optically levitated torque sensors have attracted many interests [17,18,23], an experimental demonstration of a torque sensitivity better than that of the state-of-the-art nanofabricated torque sensor (10 −24 Nm/ √ Hz) [6] has not been reported.…”

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confidence: 99%

Ultrasensitive torque detection with an optically levitated nanorotor

Ahn¹,

Xu²,

Bang³

et al. 2020

Nat. Nanotechnol.

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Torque sensors such as the torsion balance enabled the first determination of the gravitational constant by Cavendish [1] and the discovery of Coulomb's law. Torque sensors are also widely used in studying small-scale magnetism [2,3], the Casimir effect [4], and other applications [5]. Great effort has been made to improve the torque detection sensitivity by nanofabrication and cryogenic cooling. The most sensitive nanofabricated torque sensor has achieved a remarkable sensitivity of 10 −24 Nm/ √Hz at millikelvin temperatures in a dilution refrigerator [6]. Here we dramatically improve the torque detection sensitivity by developing an ultrasensitive torque sensor with an optically levitated nanorotor in vacuum. We measure a torque as small as (1.2±0.5)×10 −27 Nm in 100 seconds at room temperature. Our system does not require complex nanofabrication or cryogenic cooling. Moreover, we drive a nanoparticle to rotate at a record high speed beyond 5 GHz (300 billion rpm). Our calculations show that this system will be able to detect the long-sought vacuum friction [7-10] near a surface under realistic conditions. The optically levitated nanorotor will also have applications in studying nanoscale magnetism [2,3] and quantum geometric phase [11].

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“…While the Casimir force has been measured extensively, the Casimir torque has not been observed experimentally though it was predicted over forty years ago. Some ideas proposed recently to detect the Casimir torque with an optics (see, e. g. [61] and references therein) can be useful for the proposal of analogous experimental methods in microwaves.…”

Section: Ss Hjmentioning

confidence: 99%

Quantization of magnetoelectric fields

Kamenetskii

2019

Journal of Modern Optics

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The effect of quantum coherence involving macroscopic degree of freedom, and occurring in systems far larger than individual atoms are one of the topical fields in modern physics. Because of material dispersion, a phenomenological approach to macroscopic quantum electrodynamics, where no canonical formulation is attempted, is used. The problem becomes more complicated when geometrical forms of a material structure have to be taken into consideration. Magnetic-dipolar-mode (MDM) oscillations in a magnetically saturated quasi-2D ferrite disk are macroscopically quantized states. In this ferrimagnetic structure, long-range dipole-dipole correlation in positions of electron spins can be treated in terms of collective excitations of a system as a whole. The near fields in the proximity of a MDM ferrite disk have space and time symmetry breakings. Such MDM-originated fieldscalled magnetoelectric (ME) fieldscarry both spin and orbital angular momentums. By virtue of unique topology, ME fields are different from free-space electromagnetic (EM) fields. The ME fields are quantum fluctuations in vacuum. We call these quantized states ME photons. There are not virtual EM photons. We show that energy, spin and orbital angular momenta of MDM oscillations constitute the key physical quantities that characterize the ME-field configurations. We show that vacuum can induce a Casimir torque between a MDM ferrite disk, metal walls, and dielectric samples. PACS number(s): 41.20.Jb, 71.36.+c, 76.50.+g I.

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Detecting Casimir torque with an optically levitated nanorod

Cited by 76 publications

References 59 publications

Five-dimensional cooling and nonlinear dynamics of an optically levitated nanodumbbell

Five-dimensional cooling and nonlinear dynamics of an optically levitated nanodumbbell

Ultrasensitive torque detection with an optically levitated nanorotor

Quantization of magnetoelectric fields

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