Modelling of Nonlinear Interaction of Rb 87 Atoms with Polarized Radiation (original) (raw)
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Shape of the coherent-population-trapping resonances and high-rank polarization moments
Physical Review A, 2007
The shape of the coherent-population-trapping ͑CPT͒ resonances was investigated theoretically and experimentally at different laser powers. The CPT resonances were observed in fluorescence on the degenerate two-level system of the ͑F =2→ F f =1͒ transition of the 87 Rb D 1 line by means of a Hanle effect configuration in an uncoated vacuum cell. Numerical simulations based on the density matrix formalism, which take into account the high-rank polarization moment ͑HRPMs͒ influence and the velocity distribution of the atoms, were used to calculate the shape of the nonlinear magnetic resonances. The comparison of the theoretical and experimental shapes of the CPT resonances demonstrated that the HRPMs influence the shape at all laser excitation powers, and this influence can be used to explain some peculiarities at the center of the CPT resonance shape.
Physical Review A, 2020
Multiphoton nonlinear frequency mixing effects on coherent electromagnetically induced absorption spectra of 85mathrmRb^{85}\mathrm{Rb}85mathrmRb atoms using two orthogonal linear polarizations of strong-coupling and weak probe beams are investigated theoretically and experimentally with respect to an applied longitudinal magnetic field and coupling powers. Herein, we confirm that at least five-photon interactions in solving density matrix equations for the Fg=3ensuremathrightarrowFe=4{F}_{g}=3\ensuremath{\rightarrow}{F}_{e}=4Fg=3ensuremathrightarrowFe=4 transition of 85mathrmRb^{85}\mathrm{Rb}85mathrmRb atoms are required to explain experimentally observed coherent electromagnetically induced absorption spectra when a quantum axis is selected as the propagation direction of co-propagating coupling and probe laser beams. Distinct calculated spectral differences owing to variations in the magnetic field and coupling power between three- and five-photon interactions are confirmed. The obtained asymmetrical spectral shapes match very well with those calculated from five-pho...
Physical Review A (PRA), 2020
Multiphoton nonlinear frequency mixing effects on coherent electromagnetically induced absorption spectra of 85 Rb atoms using two orthogonal linear polarizations of strong-coupling and weak probe beams are investigated theoretically and experimentally with respect to an applied longitudinal magnetic field and coupling powers. Herein, we confirm that at least five-photon interactions in solving density matrix equations for the F g = 3 → F e = 4 transition of 85 Rb atoms are required to explain experimentally observed coherent electromagnetically induced absorption spectra when a quantum axis is selected as the propagation direction of co-propagating coupling and probe laser beams. Distinct calculated spectral differences owing to variations in the magnetic field and coupling power between three-and five-photon interactions are confirmed. The obtained asymmetrical spectral shapes match very well with those calculated from five-photon interactions considering the off-resonant F g = 3 → F e = 2, 3 transitions. Genuine coherent spectral shapes are observed with a single laser combined with two acousto-optic modulators, wherein the spectral resolution is limited because of the decoherence rate between Zeeman sublevels in the ground state from transit-time relaxation.
Implementation of a double-scanning technique for studies of the Hanle effect in rubidium vapor
The European Physical Journal D, 2007
We have studied the resonance fluorescence of a room-temperature rubidium vapor exited to the atomic 5 P 3/2 state (D2 line) by powerful single-frequency cw laser radiation (1.25 W/cm 2) in the presence of a magnetic field. In these studies, the slow, linear scanning of the laser frequency across the hyperfine transitions of the D2 line is combined with a fast linear scanning of the applied magnetic field, which allows us to record frequency-dependent Hanle resonances from all the groups of hyperfine transitions including V-and Λ-type systems. Rate equations were used to simulate fluorescence signals for 85 Rb due to circularly polarized exciting laser radiation with different mean frequency values and laser intensity values. The simulation show a dependance of the fluorescence on the magnetic field. The Doppler effect was taken into account by averaging the calculated signals over different velocity groups. Theoretical calculations give a width of the signal peak in good agreement with experiment.
Measurement and modelling of enhanced absorption Hanle effect resonances in 85 Rb
Journal of Physics B: Atomic, Molecular and Optical Physics, 2009
We report on a detailed measurement of the enhanced absorption Hanle effect resonances in 85 Rb. The effect was analysed with an experimental setup allowing for the control of each magnetic field component within 1 mG. The characterization deals with the dependence of resonances, observed under different magnetic field conditions, on the frequency, intensity and polarization of the exciting radiation field. An analytic model that precisely describes the resonance behaviour is discussed.
STUDIES OF DARK RESONANCES IN Rb ATOMS IN THE FIELD OF LIGHT PULSE TRAIN
Dark resonances in 87 Rb vapor in the field of a femtosecond laser pulse train have been studied theoretically and experimentally. Three-and four-level schemes of interaction between an 87 Rb atom and the field, which are formed by the field-coupled magnetic sublevels of states 2 S 1/2 and 3 P 3/2 of the rubidium atom have been analyzed. The position and the shape of the experimentally recorded dark resonance correspond to the results of our calculations. It has been shown that the interaction between rubidium vapor and a polychromatic field allows the signal to be enhanced substantially in comparison with that in the case of bichromatic field.
Interaction of stochastically polarized laser light with atoms
Physical Review A, 1981
This paper considers the effect of stochastic variations in the polarization of a laser tuned to resonance with the transition between a J = 0 state and the m =-1 magnetic sublevel, of a J = 1 state. The transition rate into the N = 1 sublevel, which is zero in the pure-polarization case, is calculated using two approximate methods, secondorder perturbation theory and first-order Redfield theory.
Physical Review A, 1999
Analytic solutions of the optical Bloch equations for a two-level atom interacting with a strong polychromatic field whose frequencies are symmetrically positioned with respect to the atomic frequency are used to obtain the polarization spectrum of the atom. The spectrum is found to consist of a series of discrete peaks or dips superimposed on the continuous part of the spectrum. Physical interpretation of resonances exhibited in the continuous part of the spectrum is given using a semiclassical dressed-atom approach.
Physical Review A, 2013
Photoassociation resonances in the 87 Rb 2 1 g state dissociating to 5 2 S + 5 2 P 1/2 were produced by the excitation of colliding 87 Rb atoms in a far-off resonance trap. Levels down to 31 cm −1 below the dissociation limit were measured with resonance linewidths of 15 to 20 MHz, and have been located to a one-sigma combined systematic and statistical uncertainty of 50 MHz relative to the 5 2 S + 5 2 P 1/2 limit. Electron and nuclear spins were fixed to a space-fixed axis by circularly polarized optical pumping, so that only states with total nuclear spin I = 3 were excited, thereby greatly simplifying the spectrum. The analysis of the data yielded hyperfine coupling parameters A(v), vibrational G(v), and rotational B(v) parameters. The G(v) parameters could be fit to an rms accuracy of about 0.01 cm −1 to a potential constructed from current C 3 and C 6 long-range dispersion parameters plus an ab initio potential that was adjusted in depth and with quadratic terms in the internuclear distance added to the inner wall.
Theoretical modeling of resonant laser excitation of atoms in a magnetic field
Physical Review A, 2008
The interaction of near-resonant laser radiation with atoms immersed in a magnetic B-field is calculated using a Quantum Electro-Dynamic (QED) model. In this model, the magnetic field is assumed to produce a small perturbation such that the degeneracy of the magnetic sub-states is lifted while maintaining the usual quantum numbers that define the states (the Zeeman effect). The laser radiation is considered to have a narrow bandwidth and to be temporally and spatially coherent. The model produces three general coupled differential equations that describe the state populations and their relative coherences, and the optical coherences between levels coupled by the laser radiation. The model can therefore be directly applied to different experiments ranging from atom trapping and cooling experiments, through to collision experiments carried out in magnetic and laser fields. PACS No. 34.80.Dp 1.0 Introduction. The application of laser radiation to atomic or molecular targets immersed in magnetic fields is now widely used in many different experiments. Such experiments include the production of slow atoms from effusive sources in a Zeeman slower, and the cooling and trapping of atoms to micro-Kelvin temperatures in a Magneto-Optical Trap (MOT) [1]. New collision experiments have also been performed where atoms are prepared in an excited state within a magnetic field produced by a Magnetic Angle Changing (MAC) device [2]