Tests of new physics from precise measurements of the Casimir pressure between two gold-coated plates
R. S. Decca · D. López · E. Fischbach · G. L. Klimchitskaya · D. E. Krause · V. M. Mostepanenko
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In one page
Two conducting surfaces held a few hundred nanometres apart in vacuum pull toward each other, because the boundaries reshape the zero-point field in the gap. Ricardo Decca and five colleagues measured that pull more precisely than anyone had before, using a micromechanical torsion oscillator: a gold-coated plate hanging on serpentine springs with a gold-coated sphere above it, whose resonant frequency shifts by an amount that converts straight into Casimir pressure. Averaging thirty-three runs taken at the same 293 separations, they pushed the total error down to 0.19 percent at 160 nanometres, and for the first time in this field the random scatter fell below the systematic error. They also measured the electrical properties of their own gold films instead of reading them from a table. That precision does real work: it settles a standing argument about how temperature enters the Casimir force, and it tightens by a factor of three the limit on any new short-range force added to gravity between roughly 30 and 86 nanometres.
Why it matters hereChapter 2 stands on the fact that the vacuum is measured, not merely inferred, and this is that measurement at its sharpest — a sub-one-percent laboratory reading of a force that exists only because the zero-point field is there. It also shows what the precision buys: the same apparatus that weighs the vacuum becomes a search for physics beyond the standard model.
What it claims
01A micromechanical torsion oscillator determines the Casimir pressure between two gold-coated plates with a total relative error, at 95 percent confidence, of 0.19 percent at the shortest separation of 160 nanometres rising to 9.0 percent at 750 nanometres.Abstract; introduction, third improvement paragraph
Settled physics02Repeating the sweep 33 times at practically the same 293 separations, with a two-colour fibre interferometer that repositions the sample to within 0.2 nanometres, suppressed the random error below the systematic error — a dominance never previously achieved in a Casimir force experiment.Experimental procedure; Fig. 2 error curves
Settled physics03The electronic parameters of the gold films were obtained from the measured resistivity of companion films between 3 K and 400 K rather than from tables, giving a plasma energy of 8.9 eV and a relaxation parameter of 0.0357 eV at room temperature.Film characterisation paragraph, after Eq. (2)
Published and peer-reviewed04Comparing the data with Lifshitz theory at 295 K, the Leontovich impedance approach agrees across the whole measured range, while the Drude-model approach — which predicts thermal effects of up to 16 percent of the pressure below one micrometre — is excluded at 95 percent confidence from 160 to 750 nanometres and at 99.9 percent confidence from 210 to 620 nanometres.Eqs. (3) and (4) and the following comparison paragraphs
Published and peer-reviewed05The same data set the strongest existing constraints on a Yukawa correction to the Newtonian gravitational potential for interaction ranges from 29.5 to 86 nanometres, improving earlier limits by a factor of three near 40 nanometres.Eq. (5); Fig. 3, line 1
Published and peer-reviewed06The small thermal corrections predicted by the competing calculations remain below the reach of this apparatus, so the measurement that would close the thermal Casimir question is one sensitive enough to resolve them at these separations.Closing comparison paragraph, before the summary
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Abstract
A micromechanical torsion oscillator has been used to strengthen the limits on new Yukawa forces by determining the Casimir pressure between two gold-coated plates. By significantly reducing the random errors and obtaining the electronic parameters of the gold coatings, we were able to conclusively exclude the predictions of large thermal effects below 1 µm and strengthen the constraints on Yukawa corrections to Newtonian gravity in the interaction range from 29.5 nm to 86 nm.
R. S. Decca, D. López, E. Fischbach, G. L. Klimchitskaya, D. E. Krause and V. M. Mostepanenko. Physical Review D 75, 077101 (2007). Author version: arXiv:hep-ph/0703290, 27 March 2007.
(Abstract only. The author version is free to read at https://arxiv.org/abs/hep-ph/0703290 and the published article at https://doi.org/10.1103/PhysRevD.75.077101 — see the rights note for why the full text is not reproduced here.)
The way in
https://doi.org/10.1103/PhysRevD.75.077101Licence checked directly. The published article carries the APS default license, and the author version posted as arXiv:hep-ph/0703290v1 (27 March 2007) is under arXiv’s non-exclusive distribution licence — no Creative Commons statement appears in either. Only the abstract is reproduced here; the author version is free to read on arXiv. The summary and claims below were written from the complete text of that version.
How to cite it
R. S. Decca, D. López, E. Fischbach, G. L. Klimchitskaya, D. E. Krause, V. M. Mostepanenko (2007) Tests of new physics from precise measurements of the Casimir pressure between two gold-coated plates. doi:10.1103/PhysRevD.75.077101
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