New realization of the ohm and farad using the NBS calculable capacitor

Shields, J.Q.; Dziuba, Ronald F.; Layer, Howard P.

doi:10.1109/19.192281

Cited by 40 publications

(19 citation statements)

References 11 publications

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“…One of the largest sources of uncertainty in the calculable capacitor experiment is due to geometrical imperfections in the bars, and in the alignment of the bars with each other and with the blocking electrodes. The previously reported value [3] of the relative standard uncertainty due to geometrical effects in the NIST calculable capacitor was . However, recent linearity tests, which consisted of measuring 0.1 pF increments along the length of the calculable capacitor, have resulted in the assignment of a larger uncertainty for geometrical imperfections [4].…”

Section: Introductionmentioning

confidence: 93%

Model tests to investigate the effects of geometrical imperfections on the NIST calculable capacitor

Jeffery¹,

Lee²,

Shields³

1999

IEEE Trans. Instrum. Meas.

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The calculable capacitor at National Institute of Standards and Technology (NIST) links the U.S. capacitance unit to the SI unit and has a relative standard uncertainty of 2 2 2 2 10 0 0 08 . Geometrical imperfections are one of the largest sources of this uncertainty. Tests with a model calculable capacitor have been done to better evaluate and reduce this uncertainty. These included evaluations of the effect of eccentricity of the blocking electrodes used to define the capacitor's length and of uniform taper on all the calculable capacitor bars. In addition, the effect of tilt of the blocking electrode and taper in three or fewer bars was investigated. A new cone-shape for the tip of the blocking electrode was also studied.

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Section: Introductionmentioning

confidence: 93%

Model tests to investigate the effects of geometrical imperfections on the NIST calculable capacitor

Jeffery¹,

Lee²,

Shields³

1999

IEEE Trans. Instrum. Meas.

Self Cite

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“…The fine structure constant can be deduced from experiments related to different branches of physics (QED, Solid state physics,...) [10,11,12,13,14,15]. Many of these measurements lead to determinations of α with a relative uncertainty on the order of 10 −8 but their total dispersion exceeds 10 −7 (CODATA 98, [16]).…”

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confidence: 99%

Bloch Oscillations of Ultracold Atoms: A Tool for a Metrological Determination ofh/mRb

et al. 2004

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We use Bloch oscillations in a horizontal moving standing wave to transfer a large number of photon recoils to atoms with a high efficiency (99.5% per cycle). By measuring the photon recoil of 87 Rb, using velocity selective Raman transitions to select a subrecoil velocity class and to measure the final accelerated velocity class, we have determined h/m Rb with a relative precision of 0.4 ppm. To exploit the high momentum transfer efficiency of our method, we are developing a vertical standing wave set-up. This will allow us to measure h/m Rb better than 10 −8 and hence the fine structure constant α with an uncertainty close to the most accurate value coming from the (g − 2) determination.

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“….) [29,30,31,32,33,34]. A measurement of h/m has been proposed as a candidate microgravity mission in the HYPER [27] and ICE [35] programs, as a follow-up to the state-of-the art measurements on earth using cold atoms [36,37].…”

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confidence: 99%

Coherent matter wave inertial sensors for precision measurements in space

et al. 2006

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We analyze the advantages of using ultra-cold coherent sources of atoms for matterwave interferometry in space. We present a proof-of-principle experiment that is based on an analysis of the results previously published in [1] from which we extract the ratio h/m for 87 Rb. This measurement shows that a limitation in accuracy arises due to atomic interactions within the Bose-Einstein condensate. Finally we discuss the promising role of coherent-matter-wave sensors, in particular inertial sensors, in future fundamental physics missions in space. Atom interferometry [2,3,4,5,6] has long been one of the most promising candidates for ultra-precise and ultra-accurate measurement of gravito-inertial forces [7,8,9,10,11,12,13] or for precision measurements of fundamental constants [14]. The realization of Bose-Einstein condensation (BEC) of a dilute gas of trapped atoms in a single quantum state [15,16,17] has produced the matter-wave analog of a laser in optics [18,19,20,21]. As lasers have revolutionized optical interferometry [22,23,24], so it is expected that the use of Bose-Einstein condensed atoms will bring the science of atom optics, and in particular atom interferometry, to an unprecedented level of accuracy [25,26]. In addition, BEC-based coherent atom interferometry would reach its full potential in space-based applications where micro-gravity will allow the atomic interferometers to reach their best performance [27].In this document, we discuss the prospects of using atom-lasers in future space missions to study fundamental physics. We point out that atomic ensembles at sub-microKelvin temperatures will be required, if the sensitivity of spacebased atom-interferometers is to reach its full potential. In addition, we show

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New realization of the ohm and farad using the NBS calculable capacitor

Cited by 40 publications

References 11 publications

Model tests to investigate the effects of geometrical imperfections on the NIST calculable capacitor

Model tests to investigate the effects of geometrical imperfections on the NIST calculable capacitor

Bloch Oscillations of Ultracold Atoms: A Tool for a Metrological Determination ofh/mRb

Coherent matter wave inertial sensors for precision measurements in space

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