Vacuum-polarization screening corrections to the energy levels of lithiumlike ions (original) (raw)
Physica Scripta, 1999
The quantum physics of light is a most fascinating field. Here I present a very personal viewpoint, focusing on my own path to quantum entanglement and then on to applications. I have been fascinated by quantum physics ever since I heard about it for the first time in school. The theory struck me immediately for two reasons: (1) its immense mathematical beauty, and (2) the unparalleled precision to which its predictions have been verified again and again. Particularly fascinating for me were the predictions of quantum mechanics for individual particles, individual quantum systems. Surprisingly, the experimental realization of many of these fundamental phenomena has led to novel ideas for applications. Starting from my early experiments with neutrons, I later became interested in quantum entanglement, initially focusing on multi-particle entanglement like GHZ states. This work opened the experimental possibility to do quantum teleportation and quantum hyper-dense coding. The latter became the first entanglement-based quantum experiment breaking a classical limitation. One of the most fascinating phenomena is entanglement swapping, the teleportation of an entangled state. This phenomenon is fundamentally interesting because it can entangle two pairs of particles which do not share any common past. Surprisingly, it also became an important ingredient in a number of applications, including quantum repeaters which will connect future quantum computers with each other. Another application is entanglement-based quantum cryptography where I present some recent long-distance experiments. Entanglement swapping has also been applied in very recent so-called loophole-free tests of Bell's theorem. Within the physics community such loophole-free experiments are perceived as providing nearly definitive proof that local realism is untenable. While, out of principle, local realism can never be excluded entirely, the 2015 achievements narrow down the remaining possibilities for local realistic explanations of the quantum phenomenon of entanglement in a significant way. These experiments may go down in the history books of science. Future experiments will address particularly the freedom-of-choice loophole using cosmic sources of randomness. Such experiments confirm that unconditionally secure quantum cryptography is possible, since quantum cryptography based on Bell's theorem can provide unconditional security. The fact that the experiments were loophole-free proves that an eavesdropper cannot avoid detection in an experiment that correctly follows the protocol. I finally discuss some recent experiments with single-and entangled-photon states in higher dimensions. Such experiments realized quantum entanglement between two photons, each with quantum numbers beyond 10 000 and also simultaneous entanglement of two photons where each carries more than 100 dimensions. Thus they offer the possibility of quantum communication with more than one bit or qubit per photon. The paper concludes discussing Einstein's contributions and viewpoints of quantum mechanics. Even if some of his positions are not supported by recent experiments, he has to be given credit for the fact that his analysis of fundamental issues gave rise to developments which led to a new information technology. Finally, I reflect on some of the lessons learned by the fact that
Nuclear and Electron Polarization Contributions to the HFS of Hydrogen- and Lithium-like Ions
Hyperfine Interactions, 2000
The Dynamic Correlation Model (DCM) has been used to calculate nuclear ground-state wave functions of nuclei with one particle/hole in the closed shells. The strong mixing amplitudes between the valence particle/hole and the intrinsic vacuum states (valence hole coupled to core excitations) characterize the dynamic calculations of the hyperfine-structure splitting energy of the hydrogenlike ions which are in good agreement with measured values if the QED corrections are neglected. New experiments on the hyperfine-structure splitting energies of lithium-like ions could help in clarifying this still open point.
QED corrections to the g factor of Li- and B-like ions
Physical Review A, 2020
QED corrections to the g factor of Li-like and B-like ions in a wide range of nuclear charges are presented. Many-electron contributions as well as radiative effects on the one-loop level are calculated. Contributions resulting from the interelectronic interaction, the self-energy effect, and most of the terms of the vacuum-polarization effect are evaluated to all orders in the nuclear coupling strength Zα. Uncertainties resulting from nuclear size effects, numerical computations, and uncalculated effects are discussed.
Relativistic calculations of the isotope shifts in highly charged Li-like ions
Physical Review A, 2014
Relativistic calculations of the isotope shifts of energy levels in highly charged Li-like ions are performed. The nuclear recoil (mass shift) contributions are calculated by merging the perturbative and large-scale configuration-interaction Dirac-Fock-Sturm (CI-DFS) methods. The nuclear size (field shift) contributions are evaluated by the CI-DFS method including the electron-correlation, Breit, and QED corrections. The nuclear deformation and nuclear polarization corrections to the isotope shifts in Li-like neodymium, thorium, and uranium are also considered. The results of the calculations are compared with the theoretical values obtained with other methods. arXiv:1410.7071v1 [physics.atom-ph]
Quantum calculations of Stark broadening of Li‐like ions; T and Zscaling
2008
Quantum-mechanical calculations for the electron impact Stark linewidths of the 3s-3p transitions for the lithium-like ions from C IV to Ne VIII are performed in the frame of the impact approximation and for intermediate coupling. Good agreement is obtained with experimental and other theoretical results. Dependence of Stark widths with temperature and charge has been studied.
A theoretical study on the strong-field ionization of the lithium atom
Journal of Physics B: Atomic, Molecular and Optical Physics, 2013
We apply a recently developed momentum space method (Jiang et al 2012 Phys. Rev. E 86 066702) to investigate the experimental results of strong-field ionization of the lithium atom (Schuricke et al 2011 Phys. Rev. A 83 023413). By splitting the photoelectron into groups of even and odd angular momenta and by using the states' population history, we can analyse the ionization mechanism in further detail. The lower energy double-peak structure, shown experimentally, of the photoelectron is attributed to the three-level-coupling effect. The spectral difference of 10 and 30 fs pulses at a typical intensity is demonstrated. We explain why the strong-field ionization fluctuates at intensities of 6 and 10 fs, but not for a 30 fs pulse. The change of fan-like photoelectron angular distribution with intensity in direction parallel to polarization is explained. Use of the Keldysh parameter to classify the tunnelling and multiphoton ionization is not meaningful for the lithium atom, because the ground state is mostly depleted before reaching peak intensity.
Relativistic and QED corrections to the g factor of Li-like ions
Physical Review A, 2004
Calculations of various corrections to the g factor of Li-like ions are presented, which result in a significant improvement of the theoretical accuracy in the region Z = 6 -92. The configuration-interaction Dirac-Fock method is employed for the evaluation of the interelectronic-interaction correction of order 1/Z 2 and higher. This correction is combined with the 1/Z interelectronic-interaction term derived within a rigorous QED approach. The one-electron QED corrections of first in α are calculated to all orders in the parameter αZ. The screening of QED corrections is taken into account to the leading orders in αZ and 1/Z.
The European Physical Journal D, 2009
Quantum mechanical results for the electron impact Stark widths of the 3s-3p transitions in ten Li-like ions from C IV to P XIII are carried out. The atomic structure is obtained through a scaled Thomas-Fermi-Dirac-Amaldi potential (SST numerical code) with relativistic corrections. The distorted wave method is used for the calculation of the S-Matrix, and Feshbach resonances are included by means of the Gailitis method. A comparison with other theoretical and available experimental results is done. Except for Ne VIII, we find that the agreement between our quantum results and the experiments gets better when Z increases, which is not the case for the available close-coupling quantum ones. The behavior of the Stark width with the charge Z and the electron temperature Te is also studied and in contrast to previous studies, an improved agreement with experimental Z-scaling is obtained. We show that the relative difference between widths of the two fine structure lines of the same multiplet increases with Z from 0.5% for C IV to about 12% for P XIII, proving the increasing importance of fine structure effects. The importance of the Feshbach resonances is discussed and a comparison with available semi-classical perturbation results is given.
Physical Review A, 2010
The relativistic nuclear recoil, higher-order interelectronic-interaction, and screened QED corrections to the transition energies in Li-like ions are evaluated. The calculation of the relativistic recoil effect is performed to all orders in 1/Z. The interelectronic-interaction correction to the transition energies beyond the two-photon exchange level is evaluated to all orders in 1/Z within the Breit approximation. The evaluation is carried out employing the large-scale configurationinteraction Dirac-Fock-Sturm method. The rigorous calculation of the complete gauge invariant sets of the screened self-energy and vacuum-polarization diagrams is performed utilizing a local screening potential as the zeroth-order approximation. The theoretical predictions for the 2p j − 2s transition energies are compiled and compared with available experimental data in the range of the nuclear charge number Z = 10 − 60.