New Limits on Variation of the Fine-Structure Constant Using Atomic Dysprosium

Leefer, N.; Weber, Carsten; Cingöz, A.; Torgerson, J. R.; Budker, Dmitry

doi:10.1103/physrevlett.111.060801

Cited by 122 publications

(106 citation statements)

References 36 publications

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“…The linear dependence of on gravitational potential derived from the FeV measurement is k ¼ 0:7 AE 0:3, which is much weaker than the limit derived from atomic clocks, where the best current limit is k ¼ ðÀ5:5 AE 5:2Þ Â 10 À7 [12]. The aim of this work, however, is not to find k , but to find the dependence of on gravitational potential mediated by a light scalar field.…”

Section: Prl 111 010801 (2013) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 78%

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Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

et al. 2013

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We propose a new probe of the dependence of the fine-structure constant on a strong gravitational field using metal lines in the spectra of white-dwarf stars. Comparison of laboratory spectra with far-UV astronomical spectra from the white-dwarf star G191-B2B recorded by the Hubble Space Telescope Imaging Spectrograph gives limits of Á = ¼ ð4:2 AE 1:6Þ Â 10 À5 and ðÀ6:1 AE 5:8Þ Â 10 À5 from FeV and NiV spectra, respectively, at a dimensionless gravitational potential relative to Earth of Á % 5 Â 10 À5 . With better determinations of the laboratory wavelengths of the lines employed these results could be improved by up to 2 orders of magnitude. DOI: 10.1103/PhysRevLett.111.010801 PACS numbers: 06.20.Jr, 31.15.am, 32.30.Jc, 97.20.Rp Light scalar fields can appear very naturally in modern cosmological models and theories of high-energy physics, changing parameters of the standard model such as fundamental coupling constants and mass ratios. Like the gravitational charge, the scalar charge is purely additive, so near massive objects such as white dwarfs the effect of the scalar field can change. For objects that are not too relativistic, such as stars and planets, both the total mass and the total scalar charge are simply proportional to the number of nucleons in the object. However, different types of coupling between the scalar field and other fields can lead to an increase or decrease in scalar coupling strengths near gravitating massive bodies [1]. For small variations, the scalar field variation at distance r from such an object of mass M is proportional to the change in dimensionless gravitational potential ¼ GM=rc 2 , and we express this proportionality by introducing the sensitivity parameter k [2]. Specifically, for changes in the fine-structure ''constant'' , we writeThis dependence can be seen explicitly in particular theories of varying , such as those of Bekenstein [3] and Barrow-Sandvik-Magueijo [4], and their generalizations [5], where can increase (Á = > 0) or decrease (Á = < 0) on approach to a massive object depending on the balance between electrostatic and magnetic energy in the ambient matter fields [1]. The most sensitive current limits on k come from measurements of two Earth-bound clocks over the course of a year [2,[6][7][8][9][10][11][12]. The sensitivity is entirely due to ellipticity in Earth's orbit, which gives a 3% seasonal variation in the gravitational potential at Earth due to the Sun. The peak-to-trough sinusoidal change in the potential has magnitude Á ¼ 3 Â 10 À10 . Each clock has a different sensitivity to variation, and so Á = can be measured and hence k extracted.Because of the high precision of atomic clocks, k is determined very precisely despite the relatively small seasonal change in the gravitational potential. By contrast, we examine a ''medium strength'' field, where Á is 5 orders of magnitude larger than in the Earth-bound experiments, and the distance between the probe and the source is $10 4 times smaller than 1 AU. This allows us to probe nonlinear coupling of Á...

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Section: Prl 111 010801 (2013) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 78%

“…The most sensitive current limits on k come from measurements of two Earth-bound clocks over the course of a year [2,[6][7][8][9][10][11][12]. The sensitivity is entirely due to ellipticity in Earth's orbit, which gives a 3% seasonal variation in the gravitational potential at Earth due to the Sun.…”

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confidence: 99%

Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

et al. 2013

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“…This includes the above Rb/Cs result (see sect. 4), optical frequency measurements of H(1S-2S) [45], Yb + [46], Hg + [47], Dy [48] and Sr (see above, and [23] and references therein) against Cs, and the optical-to-optical ion clock frequency ratio Al + /Hg + [49]. The fit yields independent constraints for the three constants given in the first row of the Table in fig.…”

Section: Fundamental Physics Testsmentioning

confidence: 99%

“…Similarly, we perform a global analysis for the variation with the gravitational potential exploiting all available comparisons as of October 2014 [43,47,48] and the above Rb/Cs and Sr/Cs results. The least-squares fit to these results yields independent constraints for the three couplings to gravity given in the second row of the Table in fig.…”

Section: Fundamental Physics Testsmentioning

confidence: 99%

Atomic fountains and optical clocks at SYRTE: Status and perspectives

Abgrall

Chupin

Sarlo

et al. 2015

Comptes Rendus. Physique

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In this article, we report on the work done with the LNE-SYRTE atomic clock ensemble during the last 10 years. We cover progress made in atomic fountains and in their application to timekeeping. We also cover the development of optical lattice clocks based on strontium and on mercury. We report on tests of fundamental physical laws made with these highly accurate atomic clocks. We also report on work relevant to a future possible redefinition of the SI second. IntroductionResearch on highly accurate atomic frequency standards and their applications is making fast and steady progress. The quest for ever increased accuracy is advancing hand in hand with advances in quantum physics, with better understanding and manipulation of atomic systems, with exploration of fundamental laws of nature and with the development of important services and infrastructures for science and society. The quest for increased accuracy is also a powerful incentive to innovation in such areas as lasers, laser stabilization, low noise electronics, stable oscillators, low noise detection of optical signals, fiber devices and cold-atom based instrumentation for ground or space applications. Finally, in addition to enhancing existing applications, improved accuracy leads to new applications.This article focuses on key achievements and trends of the last 10 years. Over this period of time, the first generation of laser-cooled standards, using the atomic fountain geometry, reached maturity and had large impact on international timekeeping. The typical accuracy of these frequency standards, 2 parts in 10 16 , is now permanently accessible both locally and globally. At the same time, a new generation of optical clocks showed tremendous and steady improvement, gaining more than two orders of magnitude in a decade. To date, an accuracy of 6.4 × 10 −18 [1] was reported. Similarly, major improvements occurred in many other aspects of optical frequency metrology, notably in optical frequency combs and optical fiber links.In this article, we will report on developments of the LNE-SYRTE atomic clock ensemble since our 2004 report in the Special Issue of the Comptes Rendus de l'Académie des sciences on Fundamental Metrology [2]. This work exemplifies many of the above mentioned features of research on highly accurate atomic frequency standards. We will focus on frequency standards and their impact on timescales and timekeeping, on clock comparisons, including optical-to-microwave comparisons with combs, and their applications. Several

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“…Searching for variation of the fundamental constants is an important way of testing these theories and finding new physics beyond standard model. Laboratory measurements limit the rate at which the fine structure constant α (α = e 2 /hc) varies in time to about 10 −17 per year [2,3]. On the other hand, the analysis of quasar absorption spectra shows that the fine structure constant may vary on astronomical scale along a certain direction in space forming the so called alpha-dipole [4].…”

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confidence: 99%

Optical clock sensitive to variations of the fine-structure constant based on theHo14+ion

2015

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We study the Ho 14+ ion as a candidate for extremely accurate and stable optical atomic clock which is sensitive to the time variation of the fine structure constant. We demonstrate that the proposed system has all desired features including relatively strong optical electric dipole and magnetic dipole transitions which can be used for cooling and detection. Zero quadrupole moments for the relevant states in the clock transition allows interrogating multiple ions to improve the clock stability.PACS numbers: 06.30. Ft, 06.20.Jr, 31.15.A, 32.30.Jc Theories unifying gravity with other fundamental interactions suggest a possibility for fundamental constants to vary in space or time (see, e.g. [1]). Searching for variation of the fundamental constants is an important way of testing these theories and finding new physics beyond standard model. Laboratory measurements limit the rate at which the fine structure constant α (α = e 2 /hc) varies in time to about 10 −17 per year [2,3]. On the other hand, the analysis of quasar absorption spectra shows that the fine structure constant may vary on astronomical scale along a certain direction in space forming the so called alpha-dipole [4]. Earth movement in the framework of the alpha-dipole (towards area of bigger alpha) 4f 6 5s 4f 5 s 2~4 0000 cm -1clock hfs-E1 λ~400 nm 6 H 5/2 (5) IonGround state Clock state Energy (cm −1 ) Er 14+ 4f 7 5s J = 4 4f 6 5s 2 J = 0 18555 Dy 10+ 4f 7 5p J = 3 4f 6 5p 2 J = 0 20835 Ho 14+ 4f 6 5s J = 0.5 4f 5 5s 2 J = 2.5 23800 would lead to the local time variation of α on the scale of 10 −19 per year [5]. To test the alpha-dipole hypothesis in terrestrial studies one needs a better accuracy in the laboratory measurements. The current best limit on the local time variation of α has been obtained by comparing Al + and Hg + optical clocks [2]. The result of this comparison limits time variation of alpha to (∂α/∂t)/α = (−1.6±2.3)×10 −17 yr −1 [2]), i.e. about two orders of magnitude improvement in accuracy is needed to test the alpha-dipole hypothesis. Current-best optical-clocks approach fractional uncertainty of ∼ 10 −18 [6][7][8]. However, the transitions used in these clocks are not sufficiently sensitive to the variation of α [9]. If α does change in time, the relative change δω/ω of the clock frequencies in any given period of time would be about an order of magnitude smaller than relative change in δα/α.It has been suggested in [10] to use highly-charged ions (HCI) as extremely accurate atomic clocks to probe possible variation of α. While HCIs are less sensitive to external perturbations due to their compact size, their sensitivity to variation of α is enhanced due to larger relativistic effects. In spite of the general trend of increasing energy intervals in HCIs, it is still possible to find clock transitions which are in optical range. This is due to electron energy level crossing while moving from the Modelung to the Coulomb level ordering with increasing

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New Limits on Variation of the Fine-Structure Constant Using Atomic Dysprosium

Cited by 122 publications

References 36 publications

Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

Limits on the Dependence of the Fine-Structure Constant on Gravitational Potential from White-Dwarf Spectra

Atomic fountains and optical clocks at SYRTE: Status and perspectives

Optical clock sensitive to variations of the fine-structure constant based on theHo14+ion

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