The European Physical Journal D最新文献

The 5S(rightarrow )6P transition in rubidium (Rb) at 420 nm offers the advantage of narrow linewidth and diverse applications in quantum technologies. However, the direct spectroscopy at this transition is challenging due to its weak transition strength. In this paper, we have discussed the saturated absorption spectroscopy (SAS) of Rb using the narrow-line transition at 420 nm. We have studied the effect of the temperature of the Rb cell, control beam power, and beam size on the SAS dip heights and their linewidths. Additionally, our study offers a comprehensive examination, encompassing all eight error signals of Rb for the 5 S(rightarrow )6P transition at 420 nm and 421 nm. These findings contribute valuable insights to the field of laser frequency stabilization of Rb at blue transition and can be useful in quantum technologies based on this transition.

Direct spectroscopy of Rubidium at blue transition.

Atom and, of late, molecule interferometers find application in both the crucible of fundamental research and industrial pursuits. A prevalent methodology in the construction of atom interferometers involves the utilisation of gratings fashioned from laser beams. While this approach imparts commendable precision, it is hampered by its incapacity to attain exceedingly short wavelengths and its dependence on intricate laser systems for operational efficacy. All applications require the control of matter waves, particularly the particle’s velocity. In this manuscript, we propose a continuous beam monochromator scheme reaching enormously high velocity purification with speed ratios in the order of (10^3) based on atom-surface diffraction. Beyond these high purifications, the proposed scheme simplifies the application by reducing the degree of freedom to a single angle, selecting the wanted particle’s velocity.

Orthogonal operators are a next step in the semi-empirical description of complex spectra. Orthogonality yields optimal independence and thus least correlation between the operators. The increased stability of the fitting process is used to include higher-order many-body as well as fully relativistic effects. The calculated eigenvalues are frequently an order of magnitude more accurate with respect to a conventional semi-empirical approach. The resulting eigenvectors may not only be put to use to calculate transition probabilities and g-factors, but also to calculate hyperfine structure A and B constants. We illustrate our first steps in this field with two examples of first spectra of the iron group elements. The results are compared to current experimental hyperfine structure A-values while strong and weak points of the method are discussed. In particular to be able to deal with lanthanides and actinides, the orthogonal operator method is completed with the definition of operators for equivalent p- and f-electrons.

The present article discusses some recent advances in methods of critical evaluation of experimental data on wavelengths of spectral lines and theoretical data on transition probabilities and oscillator strengths for atoms and atomic ions. In particular, recently developed new statistical approaches to estimation of uncertainties of weighted means of multiple measurements are described, and a numerical toolbox implementing these new approaches is presented. There are also some new developments in estimation of uncertainties of theoretical transition probabilities. A short review of literature implementing these new procedures is provided, including a description of the methodology.

Positron bound state properties in hydrogen cyanide are studied via many-body theory calculations that account for strong positron-electron correlations including positron-induced polarization, screening of the electron–positron Coulomb interaction, virtual-positronium formation and positron–hole repulsion. Specifically, the Dyson equation is solved using a Gaussian basis, with the positron self-energy in the field of the molecule calculated using the Bethe–Salpeter equations for the two-particle and particle–hole propagators. The present results suggest near cancellation of screening corrections to the bare polarization, and the non-negligible role of the positron–hole interaction. There are no existing measurements to compare to for HCN. Previous configuration interaction (CI) and fixed-node diffusion Monte Carlo (FN-DMC) calculations give positron binding energies in the range 35–44 meV, most of which used a single even-tempered basis centred near the nitrogen atom. Using a similar single-centre positron basis we calculate a positron binding energy of 41 meV, in good agreement. However, we find that including additional basis centres gives an improved description of the positron wave function near the nuclei, and results in a converged binding energy in the range 63–73 meV (depending on geometry and approximation to the positron–molecule correlation potential used).

In this manuscript, we investigate the enhancement of the transfer of quantum correlations from squeezed light to movable mirrors within an optomechanical system. This enhancement was achieved via the injection of squeezed light in the cavities and via intracavity squeezed light. We quantify the entanglement between mechanical oscillators via logarithmic negativity. We demonstrate that entanglement is influenced by various factors, including the gain of the parametric amplifier, the squeezing parameter characterizing the squeezed light, the rate of the phonon tunneling process, the coupling strength of the photon hopping process and the bath temperature of the mechanical oscillators. We have shown that entanglement can be improved by a convenient choice of coupling strength in the case of the photon hopping process, as well as for specified values of the gain of the parametric amplifier.

The polarization of recoil photon ((gamma ')) in the nonlinear Compton process (e + vec L rightarrow vec {gamma }' +e') in the interaction of a relativistic electron with a linearly polarized laser beam ((vec L)) is studied within the Furry picture in the lowest order, tree-level S matrix element. In particular, we consider the asymmetry of differential cross sections (mathcal{A}) for two independent axes describing the Compton process equal to the intrinsic spin variable ({xi }^f_3) that determines the polarization properties of (gamma '). The sign and absolute value of the asymmetry determine the direction and degree of (gamma ') polarization. We have analyzed the process in a wide range of laser intensity that covers existing and future experiments. Our results provide additional knowledge for studying nonlinear multi-photon effects in quantum electrodynamics and can be used in planning experiments at envisaged laser facilities.