Laser Spectroscopy of the Fine-Structure Splitting in the 2PJ3 Levels of

Abstract

The fine-structure splitting in the 2^{3}P_{J} (J=0, 1, 2) levels of ^{4}He is of great interest for tests of quantum electrodynamics and for the determination of the fine-structure constant α. The 2^{3}P_{0}-2^{3}P_{2} and 2^{3}P_{1}-2^{3}P_{2} intervals are measured by laser spectroscopy of the ^{3}P_{J}-2^{3}S_{1} transitions at 1083 nm in an atomic beam, and are determined to be 31 908 130.98±0.13 kHz and 2 291 177.56±0.19 kHz, respectively. Compared with calculations, which include terms up to α^{5}Ry, the deviation for the α-sensitive interval 2^{3}P_{0}-2^{3}P_{2} is only 0.22 kHz. It opens the window for further improvement of theoretical predictions and an independent determination of the fine-structure constant α with a precision of 2×10^{-9}.

Quantum-electrodynamic corrections to the 1s3d states of the helium atom

“…The main obstacle in achieving this goal is that the present theory of the helium fine structure [2] is not yet developed enough. Another prominent example is the recent measurement of the 2 3 P -2 3 S transition frequency with an accuracy of 1.4 kHz [3]. This accuracy is sufficient for the determination of the nuclear charge radius with a precision below 0.1%, which is better than what is expected from the muonic helium Lamb shift.…”

Precision spectroscopy of helium in a magic wavelength optical dipole trap

“…1.97 fm) are projected to be determined with sub-attometer accuracy, which should be compared to high-precision experiments in electronic helium atoms or ions.QED theory of the helium atom, with two electrons more complicated than hydrogen, has seen impressive improvements in recent years, with QED corrections up to order mα 6 now evaluated [2]. Recent experiments are in good agreement [13][14][15][16][17][18][19][20] and may allow a competitive value for the fine structure constant in the near future [21][22][23][24]. The anticipated evaluation of the next highest order corrections (mα 7 ) [2] would allow the determination of the 4 He nuclear charge radius with an accuracy better than 1%.…”

Quantum Interference Line Shifts of Broad Dipole‐Allowed Transitions

“…This result is in good agreement with a -1.2(0.1) kHz line pulling obtained from the full-fledged optical Bloch equations. For example, X. Zheng et al [59] find their result for the 2 3 S-2 3 P centroid-off by 20 combined standard deviations from the result of P. Cancio Pastor. For example, X. Zheng et al [59] find their result for the 2 3 S-2 3 P centroid-off by 20 combined standard deviations from the result of P. Cancio Pastor.…”