1,720,963 research outputs found
Data for "Acceleration sensing with magnetically levitated oscillators above a superconductor"
No full textData sets for paper titled "Acceleration sensing with magnetically levitated oscillators above a superconductor". The article has been accepted for publication in Applied Physics Letters.</span
Levitated magnetomechanical and optomechanical systems as ultra-sensitive resonators
No full textLevitated resonators are versatile systems which are extremely well isolated from their environments; unlike other conventional resonators they are not restricted by energy dissipation by being mechanically tethered to a structure. Such well isolated resonators can be used to test fundamental physics, such as testing the validity of spontaneous collapse models, or exploring the limits of Newtonian gravity on the short range scale. In this thesis, two levitated systems are presented, one based on magnetic levitation with superconductors and one using the optical gradient force to trap dielectric nanoparticles. For the magnetic levitation, permanent neodymium magnets are suspended above and inside superconducting lead traps. Magnets ranging from 30 µm radius to 0.5 mm radius are stably trapped in vacuum conditions (< 10-6 mbar), and behave as damped driven harmonic oscillators. For a 0.5 mm radius magnet sphere trapped above a superconducting lead disk, which is cooled to 5 K, we find a quality factor Q = 5500 1300 at the oscillation frequency ω0/2π = 19.4 Hz. This corresponds to an acceleration sensitivity of Saa1/2 = 1.2 ± 0.2 × 10-10 g/√Hz, for a thermal noise limited system. Such sensitivities are suitable for devising experiments to measure the gravitational interaction between record low source masses, and further sensitivity improvements are predicted with realistic experimental improvements. For 30 µm radius magnet spheres, trapped inside a lead superconducting well, we find quality factors of up to Q = 107 when cooled to 4.2 K in a liquid helium transport dewar. By transferring this setup to a 300 mK sorption refrigerator, we also find stable levitation at low pressures and temperatures, with the ability to perform feedback cooling on resonant modes. Quality factors beyond Q = 107 are anticipated to be possible in this experiment, which with suitable vibration isolation will be able to test the Continuous-Spontaneous Localization (CSL) model in previously unexplored regimes. Optical levitation of dielectric particles is also demonstrated, with silica nanosphere strapped with the gradient force by focusing a 1550 nm to a diffraction limited spot with a parabolic mirror. Fano-like anti-resonance was shown in the dynamics of the trapped particle by applying an electrostatic force when trapped at low pressure (~10-5 mbar) with the nanoparticle charged. We speculate that a noise due to the Coulomb interaction is responsible for the asymmetric line shape, although the exact origin of this noise is unknown. The stronger the Coulomb force, the more asymmetric the lineshape, meaning we could use the strength of the Fano asymmetry parameter to characterise the magnitude of static forces on the trapped particle. This opens up the possibility of using the amount of asymmetry in the lineshape to measure static forces which affect the particle motion, but are otherwise difficult to see as they can not be "switched off" to compare to zero applied force. The minimum detected Coulomb force was 2.7 ± 0.5 × 10-15 N, measured over one second, which was easily distinguishable from zero applied force. Smaller forces are in principle possible to measure with the current system, with further improvements predicted by reducing the vacuum pressure and recording for longer times. Such a static sensor could be used to measure short range interactions, such as the Casimir force, or for sensitive gravity detection
Data for "Static force characterization with Fano anti-resonance in levitated optomechanics"
No full textData associated with the research paper "Static force characterization with Fano anti-resonance in levitated optomechanics" which has been accepted for publication in Applied Physics Letters.</span
Data for "Linear cooling of a levitated micromagnetic cylinder by vibration"
No full textDatasets used to create the figures and analysis presented in the publication titled "Linear cooling of a levitated micromagnetic cylinder by vibration", published in the journal Physical Review Research. </span
Testing dissipative collapse models with a levitated micromagnet
No full textWe present experimental tests of dissipative extensions of spontaneous wave function collapse models based on a levitated micromagnet with ultralow dissipation. The spherical micromagnet, with radius R = 27 µm, is levitated by Meissner effect in a lead trap at 4.2 K and its motion is detected by a SQUID. We perform accurate ringdown measurements on the vertical translational mode with frequency 57 Hz, and infer the residual damping at vanishing pressure γ/2π < 9 µHz. From this upper limit we derive improved bounds on the dissipative versions of the CSL (continuous spontaneous localization) and the DP (Di´osi-Penrose) models. In particular, dissipative models give rise to an intrinsic damping of an isolated system with the effect parameterized by a temperature constant – the dissipative CSL model with temperatures below 1 nK is ruled out, while the dissipative DP model is excluded for temperatures below 10−13 K. Furthermore, we present the first bounds on dissipative effects in a more recent model, which relates the wave function collapse to fluctuations of a generalized complex-valued spacetime metric
Acceleration sensing with magnetically levitated oscillators above a superconductor
No full textWe experimentally demonstrate stable trapping of a permanent magnet sphere above a lead superconductor, in vacuum pressures of 4×10−8 mbar. The levitating magnet behaves as a harmonic oscillator, with frequencies in the 4-31 Hz range detected, and shows promise to be an ultrasensitive acceleration sensor. We directly apply an acceleration to the magnet with a current carrying wire, which we use to measure a background noise of ∼ 10−10 m/ √ Hz at 30.75 Hz frequency. With current experimental parameters, we find an acceleration sensitivity of S 1/2 a = 1.2 ± 0.2 × 10−10 g/ √ Hz, for a thermal noise limited system. By considering a 300 mKenvironment, at a background helium pressure of 1 × 10−10 mbar, acceleration sensitivities of S 1/2 a ∼ 3 × 10−15 g/√ Hz could be possible with ideal conditions and vibration isolation. To feasibly measure with such a sensitivity, feedback cooling must be implemented
Probing modified gravity with magnetically levitated resonators
No full textWe present an experimental procedure, based on Meissner effect levitation of neodymium ferromagnets, as a method of measuring the gravitational interactions between milligram masses. The scheme consists of two superconducting lead traps, with a magnet levitating in each trap. The levitating magnets behave as harmonic oscillators and, by carefully driving the motion of one magnet on resonance with the other, we find that it should easily be possible to measure the gravitational field produced by a 4 mg sphere, with the gravitational attraction from masses as small as 30 μg predicted to be measurable within a realistic measurement time frame. We apply this acceleration sensitivity to one concrete example and show the abilities of testing models of modified Newtonian dynamics.</p
Dataset for: Levitated Magnetomechanical and Optomechanical Systems as Ultra-Sensitive Resonators
No full textData accompanying the PhD thesis titled "Levitated Magnetomechanical and Optomechanical Systems as Ultra-Sensitive Resonators" by Christopher Timberlake.
The data files appended .trc and .csv are voltage vs time datasets that can be read and analysed using Optoanalysis (https://github.com/AshleySetter/optoanalysis). More information on each specific file is in the readme.txt file.
Some of the data presented in this thesis has been published in journal articles. The articles are:
Acceleration sensing with magnetically levitated oscillators above a superconductor, C. Timberlake, G. Gasbarri, A. Vinante, A. Setter, and H. Ulbricht, Applied Physics Letters 115, 224101 (2019).
Static force characterization with Fano anti-resonance in levitated optomechanics, C. Timberlake, M. Toros, D. Hempston, G. Winstone, M. Rashid, and H. Ulbricht, Applied Physics Letters 114, 023104 (2019).
Ultralow mechanical damping with Meissner-levitated ferromagnetic microparticles, A. Vinante, P. Falferi, G. Gasbarri, A. Setter, C. Timberlake, and H. Ulbricht, Physical Review Applied 13, 064027 (2020).</span
Data for "Testing dissipative collapse models with a levitated micromagnet"
No full textData for the journal article: Vinante, A, Gasbarri, G, Timberlake, C, Toros, M & Ulbricht, H 2020, 'Testing dissipative collapse models with a levitated micromagnet', Physical Review Research.</span
Static force characterization with Fano anti-resonance in levitated optomechanics
No full textWe demonstrate a classical analogy to the Fano anti-resonance in levitated optomechanics by applying a DC electric field. Specifically, we experimentally tune the Fano parameter by applying a DC voltage from 0 kV to 10 kV on a nearby charged needle tip. We find consistent results across negative and positive needle voltages, with the Fano line-shape feature able to exist at both higher and lower frequencies than the fundamental oscillator frequency. We can use the Fano parameter to characterize our system to be sensitive to static interactions which are ever-present. Currently, we can distinguish a static Coulomb force of 2.7 ± 0.5 × 10−15 N with the Fano parameter, which is measured with one second of integration time. Furthermore, we are able to extract the charge to mass ratio of the trapped nanoparticle
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