Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium

Abstract

Numerical ab initio variational calculations of the transition probabilities and ac Stark shifts in two-photon transitions of antiprotonic helium atoms driven by two counter-propagating laser beams are presented. We found that sub-Doppler spectroscopy is in principle possible by exciting transitions of the type (n,L)->(n-2,L-2) between antiprotonic states of principal and angular momentum quantum numbers n~L-1~35, first by using highly monochromatic, nanosecond laser beams of intensities 10^4-10^5 W/cm^2, and then by tuning the virtual intermediate state close (e.g., within 10-20 GHz) to the real state (n-1,L-1) to enhance the nonlinear transition probability. We expect that ac Stark shifts of a few MHz or more will become an important source of systematic error at fractional precisions of better than a few parts in 10^9. These shifts can in principle be minimized and even canceled by selecting an optimum combination of laser intensities and frequencies. We simulated the resonance profiles of some two-photon transitions in the regions n=30-40 of the \bar{p}^4He^+ and \bar{p} ^3He^+ isotopes to find the best conditions that would allow this.

arXiv comment18 pages 2 tables 12 figures, submitted to Phys. Rev. A

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Cited by in corpus (6)

• CODATA Recommended Values of the Fundamental Physical Constants: 2010
• Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio
• Physics at CERN's Antiproton Decelerator
• Hydrogen molecular ions for improved determination of fundamental constants
• Proposed method for laser spectroscopy of pionic helium atoms to determine the charged-pion mass
• Proposal for suppressing ac Stark shift in the He($2{}^3{S}_1\to 3{}^3{S}_1$) two-photon transition using magic wavelengths