High-precision spectroscopy of the forbidden 2 3S1 - 2 1P1 transition in quantum degenerate metastable helium

Abstract

We have measured the forbidden 2 3S1 - 2 1P1 transition at 887 nm in a quantum degenerate gas of metastable He-4 atoms confined in an optical dipole trap. The determined transition frequency is 338 133 594.4 (0.5) MHz, from which we obtain an ionization energy of the 2 1P1 state of 814 709 148.6 (0.5) MHz. This ionization energy is in disagreement by > 3 sigma with the most accurate quantum electrodynamics (QED) calculations available. Our measurements also provide a new determination of the lifetime of the 2 1P1 state of 0.551 (0.004)stat (+ 0.013,- 0.000)syst ns, which is the most accurate determination to date and in excellent agreement with theory.

10 pages, 13 figures, paper includes supplemental information. Paper submitted for review

References in corpus (6)

• High-precision measurement of the atomic mass of the electron
• Extreme ultraviolet frequency comb metrology
• Frequency metrology of helium around 1083 nm and determination of the nuclear charge radius
• Spectroscopy of atomic hydrogen. How is the Rydberg constant determined?
• Helium energy levels including $m{\alpha }^6$ corrections
• Helium 2 3S - 2 1S metrology at 1557 nm

Cited by in corpus (9)

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• QED calculation of ionization energies of $1snd$ states in helium
• Quantum electrodynamic corrections to the $1s3d$ states of the helium atom
• Doppler-free intermodulated fluorescence spectroscopy of ${}^{4}He$ $2^{3}P-3^{1,3}D$ transitions at 588 nm with a one-watt compact laser system
• Proposal for suppressing ac Stark shift in the He($2{}^3{S}_1\to 3{}^3{S}_1$) two-photon transition using magic wavelengths
• Preparation of individual magnetic sub-levels of ${}^4$He($2^3$S${}_1$) in a supersonic beam using laser optical pumping and magnetic hexapole focusing