New Determination of the Fine Structure Constant and Test of the Quantum Electrodynamics

Bouchendira, Rym; Cladé, Pierre; Guellati-Khélifa, Saïda; Nez, F.; Biraben, F.

doi:10.1103/physrevlett.106.080801

Cited by 572 publications

(645 citation statements)

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“…0.08, 0.07 and 0.016 ppb accuracy [32]. As the most precise measurement of h / M today is for Rb, i.e., 1.3 ppb [36], a factor of ten improvement in this measurement will already hit the limit set by the knowledge set by Rb mass (measured in a Penning ion trap). Helium provides more room at the bottom in challenging the presently most accurate determination of α, i.e., by applying QED to the measurement of the g-factor of the electron [39].…”

Section: Metastable Helium For Atom Interferometrymentioning

confidence: 99%

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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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Section: Metastable Helium For Atom Interferometrymentioning

confidence: 99%

“…Apart from demonstrating the 1-m wavepacket splitting, with a possible test of atom neutrality as application [35], we aim for a measurement of the fine structure constant by measuring the one-photon recoil velocity analogous to the Rb experiment in Paris [36]. He* has additional advantages here as well [37].…”

Section: Metastable Helium For Atom Interferometrymentioning

confidence: 99%

Ultracold metastable helium: Ramsey fringes and atom interferometry

et al. 2016

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“…Ramsey-Bordé interferometers, in particular, measure the mass m of an atom through the kinetic energy ω r = 2 k 2 /(2m) it gains after recoiling from the interaction with a photon ( is the reduced Planck constant). They can help redefine the kilogram [16,17] and determine the fine-structure constant [18][19][20][21][22], thereby testing the Standard Model [23,24]. The recoil frequency ω r , and therefore the signal, scales inversely with mass.…”

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Recoil-Sensitive Lithium Interferometer without a Subrecoil Sample

et al. 2017

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We report simultaneous conjugate Ramsey-Bordé interferometers with a sample of low-mass (lithium-7) atoms at 50 times the recoil temperature. We optically pump the atoms to a magnetically insensitive state using the 2S 1/2 − 2P 1/2 line. Fast stimulated Raman beam splitters address a broad velocity class and unavoidably drive two conjugate interferometers that overlap spatially. We show that detecting the summed interference signals of both interferometers, using state labeling, allows recoil measurements and suppression of phase noise from vibrations. The use of "warm" atoms allows for simple, efficient, and high-flux atom sources and broadens the applicability of recoil-sensitive interferometry to particles that remain difficult to trap and cool.

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“…Most atom-interferometry schemes benefit from a larger enclosed area, which requires high-momentum transfer beam splitters. Our scheme can be modified such that the difference in momentum betweenâ 1 andâ 2 is greater than 2@k by using some other process to transfer momentum to one of the modes (such as state dependent Bloch oscillations [7]) after the Raman superradiance beam splitter. As long as this process doesn't exchange population between the two modes, the correlations aren't effected.…”

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confidence: 99%

“…Atom interferometers are devices that exploit the wavelike properties of atomic systems, and can provide sensitive inertial measurements [1][2][3][4], as well as measurements of magnetic fields [5], the gravitational constant (G) [6], and the fine structure constant ( ) [7]. Although most state-ofthe-art atom interferometers currently utilize laser cooled thermal atoms, there are some benefits to using BoseEinstein-condensed atoms, as they provide improved visibility in configurations which require complex manipulation of the motional state such as high momentum transfer beam splitters [8].…”

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confidence: 99%

Information-Recycling Beam Splitters for Quantum Enhanced Atom Interferometry

Haine

2013

Phys. Rev. Lett.

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We propose a scheme to significantly enhance the sensitivity of atom interferometry performed with Bose-Einstein condensates. When an optical two-photon Raman transition is used to split the condensate into two modes, some information about the number of atoms in one of the modes is contained in one of the optical modes. We introduce a simple model to describe this process, and find that by processing this information in an appropriate way, the phase sensitivity of atom interferometry can be enhanced by more than a factor of 10 for realistic parameters.

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New Determination of the Fine Structure Constant and Test of the Quantum Electrodynamics

Cited by 572 publications

References 23 publications

Ultracold metastable helium: Ramsey fringes and atom interferometry

Ultracold metastable helium: Ramsey fringes and atom interferometry

Recoil-Sensitive Lithium Interferometer without a Subrecoil Sample

Information-Recycling Beam Splitters for Quantum Enhanced Atom Interferometry

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