Helium 2 3S - 2 1S metrology at 1557 nm

Abstract

An experiment is proposed to excite the 'forbidden' 1s2s 3S1 - 1s2s 1S0 magnetic dipole (M1) transition at 1557 nm in a collimated and slow atomic beam of metastable helium atoms. It is demonstrated that an excitation rate of 5000 /s can be realised with the beam of a 2W narrowband telecom fiber laser intersecting the atomic beam perpendicularly. A Doppler-limited sub-MHz spectroscopic linewidth is anticipated. Doppler-free excitation of 2% of trapped and cooled atoms may be realised in a one-dimensional optical lattice geometry, using the 2W laser both for trapping and spectroscopy. The very small (8 Hz) natural linewidth of this transition presents an opportunity for accurate tests of atomic structure calculations of the helium atom. A measurement of the 3He - 4He isotope shift allows for accurate determination of the difference in nuclear charge radius of both isotopes.

accepted for publication in Europhysics Letters

References in corpus (6)

• Laser Spectroscopic Determination of the 6He Nuclear Charge Radius
• Improved theory of helium fine structure
• Forbidden transitions in the helium atom
• A Large Atom Number Metastable Helium Bose-Einstein Condensate
• Homonuclear ionizing collisions of laser-cooled metastable helium atoms
• Fine Structure of the 1s3p ^3P_J Level in Atomic ^4He: Theory and Experiment

Cited by in corpus (7)

• Cold and trapped metastable noble gases
• Frequency metrology in quantum degenerate helium: Direct measurement of the 2 3S1 - 2 1S0 transition
• Helium energy levels including $m{\alpha }^6$ corrections
• Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy
• High-precision spectroscopy of the forbidden 2 3S1 - 2 1P1 transition in quantum degenerate metastable helium
• Magic wavelengths for the $2{}^{3}S\to 2{}^{1}S$ transition in helium
• Relativistic full-configuration-interaction calculations of magic wavelengths for the $2{}^3{S}_1\to 2{}^1{S}_0$ transition of helium isotopes