Quadrupole absorption rate for atoms in circularly-polarized optical vortices

Twisted light beams, or optical vortices, have been used to drive the circular motion of microscopic particles in optical tweezers and have been shown to generate vortices in quantum gases. Recent studies have established that electric quadrupole interactions can mediate an orbital angular momentum exchange between twisted light and the electronic degrees of freedom of atoms. Here we consider a quadrupole atomic transition mediated by a circularly-polarized optical vortex. We evaluate the transfer rate of the optical angular momentum to a $Ca^+$ ion involving the $4^2S_{1/2}\rightarrow 3^2D_{5/2}$ quadrupole transition and explain how the polarization state and the topological charge of the vortex beam determine the selection rules.Comment: 13 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:2007.0402

Quadrupole Interaction of Non-diffracting Beams with Two-Level Atoms

Recently it has been shown that the quadrupole interactions can be improved significantly as the atom interacts at near resonance with the Laguerre-Gaussian (LG) mode. In this paper, we illustrate that other kinds of optical vortex can be also led to a considerable enhancement of quadrupole interaction when the atom interacts with optical modes at near resonance. The calculations are performed on an interesting situation with Cs atom, where the process is concerned with dipole-forbidden and quadrupole-allowed transitions with a convenable choice of atomic and optical mode parameters. In this direction, we show that the quadrupole transitions can be significantly enhanced and therefore they can play an interesting role and lead to new features of atom-light interaction, which can have some constructive implications in experiments.Comment: 9 pages, 10 figure

Proučavanje atomskih prijelaza numerovom metodom u shematskom modelu

The calculation of a partial cross section in atomic collision theory when the collision is inelastic and there is not a possibility of particle exchange requires the solution of a system of coupled differential equations. The Numerov technique is applied to the solution of schematic model equations, which simulate the solution of real problems but are themselves exactly solvable. We have investigated the 32S transition in sodium as an excellent application of a near resonance and strong coupling situation in the case of two-state approximation. The results are compared with those obtained by the Bethe and resonance distortion approximations. The difference can be ascribed to the use of the set of two-channel differential equations rather than the set of three-channel equations used in other approximations, and to the simplified treatment of the interaction potentials.Računanje parcijalnih udarnih presjeka u teoriji atomskih sudara, kad je sudar neelastičan i nema izmjene čestica, zahtijeva rješavanje sustava vezanih diferencijalnih jednadžbi. Primjenjujemo Numerovu metodu za rješavanje shematskog sustava jednadžbi koje oponašaju rješenje stvarnih problema, a se mogu egzaktno riješiti. Proučavamo 32S prijelaz u natriju kao odličnu primjenu uvjeta blizu rezonancije i snažnog vezanja za slučaj približenja razmatranjem dva stanja. Ishodi računa uspoređuju se s ishodima Betheovog približenja i približnog računa ometanja rezonancije. Razlika se može pripisati primjeni dvokanalnih diferencijalnih jednadžbi umjesto trokanalnih jednadžbi u drugim približenjima i pojednostavljenim razmatranjem potencijala međudjelovanja