Electric and magnetic fields are inherently coupled in an electromagnetic wave. However, structured light beams enable their spatial separation. In particular, azimuthally polarized laser beams exhibit a localized magnetic field on-axis without the electric counterpart. A recent study by Martín-Domene [S. Martín-Domene , ] has shown that combining these beams enables the generation of locally isolated magnetic fields with a controllable direction and phase. In the present paper, we propose a method to probe and characterize such magnetic fields by studying their interaction with a single trapped atom. In order to theoretically investigate magnetic sublevel populations and their dependence on the relative orientation and phase—i.e., the —of the isolated magnetic field, we use a time-dependent density-matrix method based on the Liouville–von Neumann equation. As illustrative cases, we consider the 2 s 2 2 p 2 P 0 3 − 2 s 2 2 p 2 P 1 3 , 1 s 2 2 s 2 S 0 1 − 1 s 2 2 s 2 p P 2 3 , and 2 s 2 2 p P 1 / 2 2 − 2 s 2 2 p P 3 / 2 2 transitions in Ca 14 + 40 , Be 10 , and Ar 13 + 38 , respectively. Our results indicate that monitoring atomic populations serves as an effective tool for probing isolated vector magnetic fields, which opens avenues for studying laser-induced processes in atomic systems where electric-field suppression is critical.
According to the quantum theory of the optical-pumping cycle, one can describe the effect of a nonresonant light beam on the different Zeeman sublevels of an atomic ground state by an effective Hamiltonian
He which depends on the polarization and spectral profile of the incident light. In order to check the structure of
He, we have performed a detailed experimental study of the ground-state energy sublevels of various kinds of atoms perturbed by different types of nonresonant light beams. Attention is paid to the modification of the Zeeman structure due to
He. We have been able to obtain experimentally in the ground state of
199Hg,
201Hg, and
87Rb, Zeeman light shifts that are larger than the width of the levels due to the thermal relaxation. The removal of the Zeeman degeneracy in zero external field, due to a nonresonant light irradiation, is observed by different optical-pumping techniques; the full Zeeman diagram of the perturbed atoms is also determined when a static field ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}$ is added. We have checked that the effect of
He can be described in terms of fictitious static electric or magnetic fields. These fictitious fields can be used to act selectively on a given atomic level.
We present experimental and theoretical studies of coherent excitation of magnetic sublevels in nD states of cesium that cross in an external electric field. Coherent excitation of mFmagnetic sublevels of hyperfine F levels with DeltamF= plusmn2 leads to resonances in the linearly polarized laser induced fluorescence (LIF), while coherent excitation of magnetic sublevels with DeltamF= plusmn1 leads to alignment to orientation conversion (AOC). From the resonance signals we were able to measure atomic constants, such as the hyperfine constant A and the tensor polarizability alpha2(Auzinsh et al., 2006). AOC involves the deformation of the spatial distribution of an atom's angular momentum and is of interest as a background in certain types of experiments that search for a permanent electric dipole moment (EDM) of the electron.