An Introduction to Varying Fundamental Constants

Karshenboim, Savely G.; Peik, E.

doi:10.1007/978-3-540-40991-5_1

Cited by 13 publications

(17 citation statements)

References 22 publications

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“…This is so far the most stringent limit onα obtained from atomic clock comparisons. This result is based on a largely modelindependent analysis [30], not using assumptions on correlations between drift rates of different quantities and not postulating the drift rate of any quantity to be zero. The intercept of the straight line of optical frequency drift rate with the line a = 0 (cf.…”

Section: −15mentioning

confidence: 95%

“…Under the assumption that the drift of the cesium frequency is linear in time over the duration of the optical frequency comparisons, the drift rate ∂ ln α/∂t can be obtained from at least two measured drift rates of transition frequencies ∂ ln f/∂t if these have been measured against cesium clocks, and if the sensitivity factors a for the two transitions are sufficiently different. As noted in [29] and in the introduction by Karshenboim and Peik in this book [30], the plot of ∂ ln f/∂t as a function of a should then yield a straight line where the slope is exclusively determined by ∂ ln α/∂t and any drifts of the duration of the SI second relative to a common scaling factor like the Rydberg constant would show up in the intercept (cf. Fig.…”

Section: Search For Temporal Variation Of the Fine-structure Constantmentioning

confidence: 96%

“…The 1σ limit that we can deduce for this quantity is (−1.0 ± 3.7) · 10 −15 1/yr. This quantity is related to the magnetic moment of the Cs nucleus, but, as discussed earlier in this book [30], there is no straightforward relation to fundamental constants.…”

Section: −15mentioning

confidence: 97%

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Trapped Ion Optical Frequency Standards for Laboratory Tests of Alpha-Variability

Tamm

Schneider

Peik

2004

Astrophysics, Clocks and Fundamental Constants

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Abstract. Optical transition frequencies of trapped laser-cooled ions have been measured so far with an uncertainty of 10 −14 with reference to primary cesium clocks. Systematic frequency shifts in these systems should be controllable to significantly higher accuracy. We have performed comparisons between frequency standards based on two independently stored 171 Yb + ions. The present experimental results indicate a relative instability (Allan standard deviation) of the optical frequency difference between the two systems of 1.0·10−15 at an averaging time of 1000 s and a mean frequency difference of 0.2 Hz for the reference frequency of 688 THz. Monitoring the absolute transition frequency over a period of a few years at this level of accuracy will lead to a stringent limit on the present value of the temporal derivative of the fine-structure constant. First results have been obtained with a frequency standard based on 199 Hg + at NIST and, more recently, also with Yb + . The combination of results obtained with different transitions can be used to separate the electronic and nuclear contributions to a drift of a transition frequency. We propose optical spectroscopy of a nuclear transition in 229 Th 3+ as a means for a precision monitoring of possible temporal variations in the strength of the nuclear forces.

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Section: −15mentioning

confidence: 95%

Section: Search For Temporal Variation Of the Fine-structure Constantmentioning

confidence: 96%

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Trapped Ion Optical Frequency Standards for Laboratory Tests of Alpha-Variability

Tamm

Schneider

Peik

2004

Astrophysics, Clocks and Fundamental Constants

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“…Significant changes of α or µ would produce a clear signature in these experiments, because they would influence the transition frequencies differently [4,26]. Atomic gross structure scales with the Rydberg constant R ∞ , hyperfine structure with the product of α 2 R ∞ and the nuclear magnetic moment.…”

Section: Search For Variations Of Constants In Astrophysics and With mentioning

confidence: 97%

Laboratory Limits for Temporal Variations of Fundamental Constants: An Update

Peik¹,

Lipphardt²,

Schnatz³

et al. 2008

The Eleventh Marcel Grossmann Meeting

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Precision comparisons of different atomic frequency standards over a period of a few years can be used for a sensitive search for temporal variations of fundamental constants. We present recent frequency measurements of the 688 THz transition in the 171 Yb + ion. For this transition frequency a record over six years is now available, showing that a possible frequency drift relative to a cesium clock can be constrained to (−0.54 ± 0.97) Hz/yr, i.e. at the level of 2 · 10 −15 per year. Combined with precision frequency measurements of an optical frequency in 199 Hg + and of the hyperfine ground state splitting in 87 Rb a stringent limit on temporal variations of the fine structure constant α: d ln α/dt = (−0.26 ± 0.39) · 10 −15 yr −1 and a model-dependent limit for variations of the proton-to-electron mass ratio µ in the present epoch can be derived:−15 yr −1 . We discuss these results in the context of astrophysical observations that apparently indicate changes in both of these constants over the last 5-10 billion years. Search for variations of constants in astrophysics and with atomic clocksOver the past few years there has been great interest in the possibility that the fundamental constants of nature might show temporal variations over cosmological time scales [1,2,3,4,5]. Such an effect -as incompatible as it seems with the present foundations of physics -appears quite naturally in the attempt to find a unified theory of the fundamental interactions. An active search for an indication of variable constants is pursued mainly in two areas: observational astrophysics and laboratory experiments with atomic frequency standards. The two most important quantities under test are Sommerfeld's fine structure constant α = e 2 /(4πǫ 0h c) and the proton-to-electron mass ratio µ = m p /m e . While α is the coupling constant of the electromagnetic interaction, µ also depends on the strength of the strong force and on the quark masses via the proton mass. It is important that these quantities are dimensionless numbers so that results can be interpreted independently from the conventions of a specific system of units. Quite conveniently, both constants appear prominently in atomic and molecular transition energies: α in atomic fine structure splittings and other relativistic contributions, and µ in molecular vibration and rotation frequencies as well as in hyperfine structure.A multitude of data on variations of α and µ has been obtained from astrophysical observations but the present picture that is obtained is not completely consistent: Evidence for a variation of α has been derived from a shift of wavelengths of metal ion absorption lines produced by interstellar clouds in the light from distant quasars [6]. These observations suggest that about 10 billion years ago (redshift range 0.5 < z < 3.5), the value of α was 1

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“…. ) attempting either to establish a Grand Unification Theory beyond the Standard Model or to reconcile this latter and General Relativity in a Theory of Everything [2,3,4,5]. Since variation of dimensional constants cannot be distinguished from that of the units, it makes more sense to consider changes of dimensionless parameters.…”

Section: Introductionmentioning

confidence: 99%

Assessing the time constancy of the proton-to-electron mass ratio by precision ro-vibrational spectroscopy of a cold molecular beam

Amato

Sarno

Ricciardi

et al. 2014

Journal of Molecular Spectroscopy

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We report the design of an experiment that aims to constrain, over a-fewyear timescale, the fractional temporal variation of the proton-to-electron mass ratio, β = m p /m e , at a level of 10 −15 /yr by means of a spectroscopic frequency measurement on a beam of cold CF 3 H molecules. This is extracted from a buffer-gas-cooling source and then collimated by means of an electrostatic hexapole lens. Employed in a two-photon Ramsey-fringes interrogation scheme, the probe source is based on a mid-infrared quantum cascade laser, phase-locked to a specially-developed optical frequency comb that is ultimately referenced to the Cs primary standard via an optical fiber link.

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An Introduction to Varying Fundamental Constants

Cited by 13 publications

References 22 publications

Trapped Ion Optical Frequency Standards for Laboratory Tests of Alpha-Variability

Trapped Ion Optical Frequency Standards for Laboratory Tests of Alpha-Variability

Laboratory Limits for Temporal Variations of Fundamental Constants: An Update

Assessing the time constancy of the proton-to-electron mass ratio by precision ro-vibrational spectroscopy of a cold molecular beam

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