The current status of bound state quantum electrodynamics calculations of transition
energies for few-electron ions is reviewed. Evaluation of one and two body QED correction …

The technique of quantum electrodynamics (QED) calculations of energy levels in the
helium atom is reviewed. The calculations start with the solution of the Schrödinger equation …

We critically examine the current status of theoretical calculations of the energies, the fine
structure, and the isotope shift of the lowest-lying states of helium, searching for unresolved …

The very high precision of current measurements and theory predictions of spectral lines in
few-electron atoms allows us to efficiently probe the existence of exotic forces between …

Improvements in both theory and frequency metrology of few-electron systems such as
hydrogen and helium have enabled increasingly sensitive tests of quantum …

Helium (He) is the ideal atom to perform tests of ab initio calculations in two-electron
systems that consider all known effects, including quantum-electrodynamics and nuclear …

With this work we start a project calculating the QED contribution of order α 7 m to the 2 P 3–
2 S 3 transition energy in helium, aiming for an accurate determination of the nuclear charge …

The hyperfine structures of the 2 S 3 1 states of the Li+ 6 and Li+ 7 ions are investigated
theoretically to extract the Zemach radii of the Li 6 and Li 7 nuclei by comparing with …

We have measured the forbidden 2 S 1 3→ 2 P 1 1 transition at 887 nm in a quantum
degenerate gas of metastable He 4 atoms confined in an optical dipole trap. The determined …

Quantum electrodynamical (QED) calculations of ionization energies of the 1 snd D states
are performed for the helium atom. We reproduce the previously known relativistic and QED …