High-precision measurement of the atomic mass of the electron

Sturm, Sven; Köhler, Florian; Zatorski, Jacek; Wagner, Anke; Harman, Z.; Werth, G.; Quint, W.; Keitel, Christoph H.; Blaum, Klaus

doi:10.1038/nature13026

Cited by 319 publications

(352 citation statements)

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“…Although it has been obtained by extrapolation of numerical results, we aim to calculate it directly, in order to find out the best approach for the analogous two-loop contribution, which currently is the main source of the uncertainty of theoretical predictions. Due to extremely accurate measurements in hydrogenlike carbon [8], the bound electron g factor is presently used for the most accurate determination of the electron mass [9], and in the future it can be used for determination of the fine structure constant [10] and for precision tests of the Standard Model.…”

Section: Introductionmentioning

confidence: 99%

One-loop binding corrections to the electron g factor

Pachucki

Puchalski

2017

Phys. Rev. A

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Section: Introductionmentioning

confidence: 99%

One-loop binding corrections to the electron g factor

Pachucki

Puchalski

2017

Phys. Rev. A

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“…In this Letter we propose a weighted difference of the g-factors of low-Z ions, for which a much stronger cancelation of nuclear effects can be achieved. The low-Z region also seems favorable from the experimental point of view, since experiments so far concentrated in this regime [9][10][11].Measurements of the g-factor of H-like ions have reached the fractional level of accuracy of 3 × 10 −11 [9]. Experiments have also been performed for Li-like ions [10].…”

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gFactor of Light Ions for an Improved Determination of the Fine-Structure Constant

et al. 2016

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A weighted difference of the g-factors of the H-and Li-like ions of the same element is theoretically studied and optimized in order to maximize the cancelation of nuclear effects between the two charge states. We show that this weighted difference and its combination for two different elements can be used to extract a value for the fine-structure constant from near-future bound-electron g-factor experiments with an accuracy competitive with or better than the present literature value. PACS numbers: 06.20.Jr, 21.10.Ky, 31.30.jn, 31.15.ac, 32.10.Dk Precision measurements of the free-electron g-factor have enabled determination of the fine-structure constant α to a high accuracy [1, 2]. An independent value of α may be extracted from the measurement of the g-factor of an electron bound in an H-like ion. This can be accomplished by identifying the leading relativistic (Dirac) contribution g D = 2 /3 1 + 2 1 − (Zα) 2 , with Z being the nuclear charge number, after subtracting corrections induced by quantum electrodynamics (QED) and nuclear effects from the measured value. The sensitivity of g D to α is largest for heavy ions. For these ions, however, nuclear effects (charge distributions, polarizabilities etc.) are not well understood and set a limitation on the ultimate accuracy of such determination.In Ref.[3], it was suggested to use a weighted difference of the g-factors of the H-and Li-like charge states of the same element in order to reduce the nuclear size effect by about two orders of magnitude for high-Z ions. In Ref.[4] (see also [5]), a specific weighted difference of the g-factors of heavy H-and B-like ions with the same Z was put forward. It was demonstrated that the theoretical uncertainty of the nuclear size effect in this difference can be brought down to 4 × 10 −10 for heavy ions around Pb, which was several times smaller than the uncertainty due to α at that time. Since then, however, the uncertainty of α was reduced by an order of magnitude [6][7][8], making it more difficult to access α in such experiments. In this Letter we propose a weighted difference of the g-factors of low-Z ions, for which a much stronger cancelation of nuclear effects can be achieved. The low-Z region also seems favorable from the experimental point of view, since experiments so far concentrated in this regime [9][10][11].Measurements of the g-factor of H-like ions have reached the fractional level of accuracy of 3 × 10 −11 [9]. Experiments have also been performed for Li-like ions [10]. In the future, it should be possible to perform experiments not only with a single ion in the trap, but also with several ions simultaneously. Such a setup will directly access differences of g-factors of different ions, greatly reducing systematic uncertainties and possibly gaining two orders of magnitude in accuracy [12]. Such experiments, complemented by corresponding improvements in the theoretical description, would become sensitive to the uncertainty of α.In the present Letter we put forward a method to extract α to higher accura...

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“…He* has additional advantages here as well [37]. The fine structure constant can be deduced from the relation The Rydberg constant R ∞ is presently known with 0.006 ppb accuracy, the electron mass in atomic units m e /m u with 0.03 ppb accuracy [38] and the atomic masses M X /m u for X = Rb, Cs and He with resp. 0.08, 0.07 and 0.016 ppb accuracy [32].…”

Section: Metastable Helium For Atom Interferometrymentioning

confidence: 99%

Ultracold metastable helium: Ramsey fringes and atom interferometry

et al. 2016

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equation cannot be solved exactly. Level energies are therefore more difficult to calculate than for atomic hydrogen showing a more stringent test of atomic physics theory. Calculations of level energies and transition frequencies have pushed our understanding of atomic physics since the twenties of last century. A major breakthrough occurred in the nineties with the advent of variational calculations in a double basis set in correlated form for the electrons, adding relativistic and quantum electrodynamics (QED) terms in orders of the fine structure constant α and the reduced electron to helium mass ratio µ/M He [1, 2]. As nonrelativistic calculations can now be performed to virtually arbitrary precision, measurements of level energies nowadays are sensitive to QED and nuclear size effects. As these effects are strongest for S-states and small principle quantum number n, the n 1,3 S states are theoretically the most promising to test QED. In particular the n = 2 states are important for high-resolution spectroscopy as these also show long lifetimes, 7800 s for the 2 3 S 1 state and 20 ms for the 2 1 S 0 state (natural linewidth 8 Hz), while the 2 3 P state has, for an allowed electric dipole transition, a relatively long lifetime of 98 ns (natural linewidth 1.6 MHz). A helium level scheme is shown in Fig. 1.Transition frequencies in helium can nowadays be measured more accurately than calculated, where the theoretical limitation is in the calculation of high-order QED terms. This hampers extraction of the charge radius of the helium nucleus (the alpha-particle for 4 He and the helion for 3 He ) from transition frequencies with an accuracy that can compete with other experiments. However, in calculating transition isotope shifts between 4 He and 3 He, QED terms cancel to a large extent, allowing very accurate extraction of the difference in the (squared) nuclear charge radii of the alpha-particle and the helion. This is particularly interesting in relation to the proton size puzzle [3][4][5]. To help solving Abstract We report on interference studies in the internal and external degrees of freedom of metastable triplet helium atoms trapped near quantum degeneracy in a 1.5 µm optical dipole trap. Applying a single π/2 rf pulse we demonstrate that 50% of the atoms initially in the m = +1 state can be transferred to the magnetic field insensitive m = 0 state. Two π/2 pulses with varying time delay allow a Ramsey-type measurement of the Zeeman shift for a high precision measurement of the 2 3 S 1 -2 1 S 0 transition frequency. We show that this method also allows strong suppression of mean-field effects on the measurement of the Zeeman shift, which is necessary to reach the accuracy goal of 0.1 kHz on the absolute transition frequencies. Theoretically the feasibility of using metastable triplet helium atoms in the m = 0 state for atom interferometry is studied demonstrating favorable conditions, compared to the alkali atoms that are used traditionally, for a non-QED determination of the fine structure constant.

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High-precision measurement of the atomic mass of the electron

Cited by 319 publications

References 27 publications

One-loop binding corrections to the electron g factor

One-loop binding corrections to the electron g factor

gFactor of Light Ions for an Improved Determination of the Fine-Structure Constant

Ultracold metastable helium: Ramsey fringes and atom interferometry

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