Precise Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">J</mml:mi><mml:mspace /><mml:mo>=</mml:mo><mml:mspace /><mml:mn>1</mml:mn><mml:mn /></mml:math>to<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">J</mml:mi><mml:mspace /><mml:mo>=</mml:mo><mml:mspace /><mml:mn>2</mml:mn><mml:mn /></mml:math>Fine Structure Interval in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"

Castillega, Jaime; Livingston, Drake; Sanders, Aric W.; Shiner, David

doi:10.1103/physrevlett.84.4321

Cited by 85 publications

(88 citation statements)

References 31 publications

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“…Reference [49] summarizes the corrections and present status of measurements of the helium 2 3 P 1 → 2 3 P 2 interval, and we use the weighted average of the corrected results of Refs. [38,41,50,51] to determine the experimental value for the 2 3 P 1 → 2 3 P 2 transition frequency. On the other hand, the theoretical uncertainties of the 2 3 S 1 − 2 3 P 0,1,2 transition frequencies are so large that the interference effect can be neglected in these cases.…”

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confidence: 99%

Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

et al. 2017

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Agreement between theoretical calculations of atomic structure and spectroscopic measurements is used to constrain possible contribution of exotic spin-dependent interactions between electrons to the energy differences between states in helium-4. In particular, constraints on dipole-dipole interactions associated with the exchange of pseudoscalar bosons (such as axions or axion-like particles, ALPs) with masses 10 −2 eV m 10 4 eV are improved by a factor of ∼ 100. The first atomic-scale constraints on several exotic velocity-dependent dipole-dipole interactions are established as well. The most commonly employed framework for the purpose of comparing different experimental searches for exotic spin-dependent interactions is that introduced in Ref.[1] to describe long-range spin-dependent potentials associated with the axion and extended in Ref.[2] to encompass long-range potentials associated with any generic spin-0 or spin-1 boson. The spin-dependent potentials enumerated in Ref. [2] are characterized by dimensionless coupling constants that specify the strength of the interaction between various particles and a characteristic range λ for the interaction associated with the reduced Compton wavelength of the new boson of mass m 0 , λ = /(m 0 c), where is the reduced Planck constant and c is the speed of light. Depending on the nature of the new interaction, different particles will have different coupling constants. In the present work, we study dipole-dipole interactions between electrons at the atomic scale through investigation of the electronic structure of helium-4.Laboratory searches for exotic spin-dependent interactions mediated by new bosons are sensitive and broadly inclusive probes for global symmetries broken at high energy scales [1,2]. For example, the fundamental proper- * Electronic address: filip.ficek@student.uj.edu.pl ties of axions and the axion-like-particles (ALPs) mentioned above [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] are characterized by a symmetry breaking scale f a and an interaction scale Λ. These scales determine, for example, the mass of the ALPand the interaction of an ALP with a Standard Model fermion X is proportional to m X c 2 /f a where m X is the fermion mass. In particular, this work improves laboratory constraints on exotic spin-spin forces between electrons mediated by bosons in the mass range between 10 −2 eV and 10 4 eV by two orders of magnitude. Our research is complementary to experiments searching for an axion/ALP coupling to photons, such as the Axion Dark Matter eXperiment (ADMX) [26], the CERN Axion Solar Telescope (CAST) [27], and light-shining-throughwall experiments such as the Any Light Particle Search (ALPS) [28], since He spectroscopy probes the electron-ALP interaction as opposed to the photon-ALP interaction and is sensitive to a mass range beyond that probed by experiments such as ADMX, CAST, and ALPS. Although star cooling rates constrain certain broad classes of ALPs [29,30], there are a number of loopholes in the astrophysica...

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Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

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“…When we include the atomic fine structure in the Hamiltonian [18], the coupling gives rise to three distinct asymptotes and to anti-crossings between attractive and repulsive curves, leading to purely long-range potential wells [25]. We construct the fine-structure coupling phenomenologically from 2 3 P splittings that have been measured accurately [19,20]. If there is no rotation, only the projection Ω of the total electronic angular momentum on the molecular axis remains a good quantum number.…”

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Giant Helium Dimers Produced by Photoassociation of Ultracold Metastable Atoms

et al. 2003

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We produce giant helium dimers by photoassociation of metastable helium atoms in a magnetically trapped, ultracold cloud. The photoassociation laser is detuned red of the atomic 2 3 S1−2 3 P0 line and produces strong heating of the sample when resonant with molecular bound states. The temperature of the cloud serves as an indicator of the molecular spectrum. We report good agreement between our spectroscopic measurements and our calculations of the five bound states belonging to a 0 + u purely long-range potential well. These previously unobserved states have classical inner turning points of about 150 a0 and outer turning points as large as 1150 a0.PACS numbers: 34.20. Cf, 32.80.Pj, 34.50.Gb In the purely long-range molecules first proposed by Stwalley et al.[1], the binding potential depends only on the long-range part of the atom-atom interaction, and the internuclear distance is always large compared with ordinary chemical bond lengths. Theoretical description of these molecules involves only the leading C 3 /R 3 terms of the electric dipole-dipole interaction and the fine structure inside each atom. These well-known interactions allow precise calculation of potential wells and rovibrational energies. Previous experimental studies of such spectra in alkali atoms have utilized the technique of laser-induced photoassociation (PA) in a magneto-optical trap (MOT) [2,3]. In addition to testing calculations of molecular structure, that work has produced precise measurements of excited-state lifetimes [4,5,6,7] and has led to accurate determinations of s-wave scattering lengths for alkali systems, which are of interest for studies of Bose Einstein condensates (BECs) [8,9]. This letter reports novel spectroscopic measurements and calculations for extraordinarily long-range molecules that are produced when two 4 He atoms in the metastable 2 3 S 1 state absorb laser light tuned close to the 2 3 S 1 − 2 3 P 0 (D 0 ) atomic line at λ = 1083 nm. As compared with the alkali dimers considered previously, the potential wells are shallower, and molecules are much more tenuous, with an internuclear distance reaching values as large as 1150 a 0 (a 0 ≃ 0.53Å, the Bohr radius). At such large distances, retardation clearly influences the dipole-dipole interaction. Moreover, these purely longrange molecular states of metastable helium are distinctive in that each atom carries a high internal energy (the 2 3 S 1 state lies 20 eV above the ground state). While one normally expects Penning ionization to destabilize such * Electronic address: leonard@lkb.ens.fr † Permanent address: Calvin College, Grand Rapids, MI, USA. ‡ Permanent address: FOM instituut voor plasmafysica Rijnhuizen, and University of Twente, The Netherlands. § Present address: Institut für Quantenoptik, Universität Hannover, Germany.energetic molecules, we note that purely long-range interactions might rather suppress this process, since the atoms are effectively held apart by the same potential that binds them together. The absence of purely longrange resonances ...

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“…For many purposes the triplet metastable state of helium can be regarded as a second ground state, one far more accessible to experimenters than the 1 1 S state, so it has been the focus of much recent activity [2,3,4,5,6,7,8,9,40]. Continued advances in the theory of two-electron quantum electrodynamic (QED) and relativistic corrections have been spurred by improved experimental results, and particularly by the prospect of obtaining an improved value for the fine-structure constant from newly obtained and extremely accurate measurements of transitions between the triplet n=2 and n=3 states [6], assuming that present inconsistencies in the theoretical work can be resolved [7,8].…”

Section: Triplet Spectramentioning

confidence: 99%

“…Overall, experiment and theory are in reasonable agreement, although for many energy levels the theoretical uncertainties are smaller than the experimental ones. In a few important cases significant discrepancies arise, most notably for the fine structure of the 2 3 P state [2,3,4,5,6,7,8,9]. Of special interest is the ionization energy (IE) of the ground 1 1 S 0 state of 4 He, which provides a sensitive test of QED corrections for a two-electron system.…”

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confidence: 99%

Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy

et al. 2007

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Abstract. We analyze several possibilities for precisely measuring electronic transitions in atomic helium by the direct use of phase-stabilized femtosecond frequency combs. Because the comb is self-calibrating and can be shifted into the ultraviolet spectral region via harmonic generation, it offers the prospect of greatly improved accuracy for UV and far-UV transitions. To take advantage of this accuracy an ultracold helium sample is needed. For measurements of the triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap metastable 2 3 S state atoms. We analyze schemes for measuring the two-photon 2 3 S → 4 3 S interval, and for resonant two-photon excitation to high Rydberg states, 2 3 S → 3 3 P → n 3 S, D. We also analyze experiments on the singlet-state spectrum. To accomplish this we propose schemes for producing and trapping ultracold helium in the 1 1 S or 2 1 S state via intercombination transitions. A particularly intriguing scenario is the possibility of measuring the 1 1 S → 2 1 S transition with extremely high accuracy by use of two-photon excitation in a magic wavelength trap that operates identically for both states. We predict a "triple magic wavelength" at 412 nm that could facilitate numerous experiments on trapped helium atoms, because here the polarizabilities of the 1 1 S, 2 1 S and 2 3 S states are all similar, small, and positive.

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Precise Measurement of theJ=1toJ=2Fine Structure Interval in the

Cited by 85 publications

References 31 publications

Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

Constraints on exotic spin-dependent interactions between electrons from helium fine-structure spectroscopy

Giant Helium Dimers Produced by Photoassociation of Ultracold Metastable Atoms

Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy

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