Search

Highly charged ions (HCIs) have drawn significant interest in quantum metrology and in the search for new physics. Among these, Ni^{12+} is considered as one of the most promising candidates for the next generation of HCI optical clocks, due to its two E1-forbidden transitions M1 and E2, which occur in the visible spectral range. In this work, we used the Shanghai-Wuhan electron beam ion trap to perform a high-precision measurement of the M1 transition wavelength. Our approach involved an improved calibration scheme for the spectra, utilizing auxiliary Ar^{+} lines for calibration and correction. Our final measured result of the M1 transition wavelength demonstrates a fivefold improvement in accuracy compared to our previous findings, reaching the subpicometer level accuracy. In combination with our rigorous atomic-structure calculations to capture the electron correlations and relativistic effects, the quantum electrodynamic corrections were extracted.

For the first time, we experimentally determine the infrared magic wavelength for the ^40 Ca ^+ $4s{\,^2}{S_{1/2}} \to 3d{\,^2}{D_{5/2}}$ electric quadrupole transition by observation of the light shift canceling in ^40 Ca ^+ optical clock. A ‘magic’ magnetic field direction is chosen to make the magic wavelength insensitive to both the linear polarization purity and the polarization direction of the laser. The determined magic wavelength for this transition is 1056.37(9) nm, which is not only in good agreement with theoretical predictions (‘Dirac–Fock plus core polarization’ method) but also more precise by a factor of about 300. Using this measured magic wavelength, we also derive the differential static polarizability to be −44.32(32) a.u., which will be an important input for the evaluation of the blackbody radiation shift at room temperatures. Our work paves a way for all-optical-trapping of ^40 Ca ^+ optical clock.

An accurate one-centre method is here applied to the calculation of the equilibrium distances and the energies for the hydrogen molecular ion in magnetic fields ranging from 109G to 4.414 × 1013 G. Both the radial and angular wavefunctions were expanded in terms of optimization B-splines. The slow convergence problem in the general one-centre method and singularities at the nuclear positions of the H+2 were solved well. The accuracy of the one-centre method has been improved in this way. We compared our results with those generated by high-precision methods from published studies. Equilibrium distances of the 1σg,u, 1πg,u, 1δg,u and 2σg states of the +2 in strong magnetic fields were found to be accurate to three to four significant digits at least up to 2.35 × 1012 G, even for the antibonding states 1σu, 1πg and 1δu, whose equilibrium distances Req are very large. [ABSTRACT FROM AUTHOR]

We have studied the geometry and resonances of the e+He(3Se) system in the framework of hyperspherical coordinates. A model potential proposed by us is used to describe the interaction between the out electron with the He+ ionic core. The calculated binding energy and expectation distance of the system are in agreement with other calculations. In addition, two resonances below the e+-He(1s2s3Se) threshold and one resonance below the Ps(n=2)-He+ threshold are identified. [ABSTRACT FROM AUTHOR]

We have performed a three-body calculation for investigation of S-wave resonances in the positron-helium scattering in the hyperspherical coordinates. B-splines are used to obtain accurate hyperspherical potential curves and channel functions. An adiabatical hyperspherical approach is used to predict semi-quantitatively the position of the resonances. A multichannel calculation with the stabilization method is also used to extract accurately the positions and widths of resonances. We find four resonances associated with the He+-Ps(n = 2) channel. The resonance parameters for the lowest two resonances are in reasonable agreement with the calculations of Kar and Ho (2004 J. Phys. B: At. Mol. Opt. Phys. 37 3177), and two more new resonances below the Ps(n = 2) threshold are identified. [ABSTRACT FROM AUTHOR]

We search for the existence of the weakly bound He-He-Mg molecules. The He-He-Mg molecule is treated as a three-body system. By using hyperspherical coordinates, the Schrödinger equation for the triatomic system is solved in the adiabatic approximation. We obtain that the binding of the three atoms is possible. The binding energies of such molecules are estimated. [ABSTRACT FROM AUTHOR]