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1
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Stark-Chirped Rapid Adiabatic Passage in a Multilevel Atom

100%
Radonjić M., Jelenković B.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
476-478
EN
We generalize Stark-chirped rapid adiabatic passage to the case of a multilevel atom. The atom is assumed to have two ground state levels g and f and an excited level e. The adiabatic passage is carried out by resonantly driving the g-e and f-e transitions with time-dependent pump and Stokes fields in the presence of strong far-off-resonant Stark field. Our formalism determines the states that participate in population transfer and is applicable to systems with arbitrary numbers of degenerate states in each level and arbitrary couplings of the g-e and f-e transitions. We give an application to adiabatic passage in Rb atom.
2
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Perturbative Solution of Optical Bloch Equations for Analysis of Electromagnetically Induced Absorption

81%
Dimitrijević J., Arsenović D., Jelenković B.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
468-470
EN
We study phenomenon of electromagnetically induced absorption in the Hanle configuration by solving time-dependent optical Bloch equations for the case of the closed multilevel F_g=1 → F_e=2 transition. Our model gives optical Bloch equations as a non-homogeneous system of ordinary linear differential equations. For weak laser fields (Ω ≪ Γ i.e. Rabi frequency small compared to spontaneous emission rate), a perturbative method to solve linear differential equations can be applied. Perturbative method is realized by solving (in the time-domain) higher-order corrections to the density matrix which in the sum converge to the exact solution of optical Bloch equations. By its form, each successive correction is also system of ordinary linear differential equations which depends on the solution of previous ones. Corrections are partitioned such that odd give corrections to optical coherences, while even give corrections to populations and Zeeman coherences. We present numerical results for the behavior of density matrix elements with successive corrections, and compare them with exact solution of optical Bloch equations. Electromagnetically induced absorption is observed as a 4th and higher (even) correction to populations, when behavior in respect to both time and magnetic field is viewed. Since in our method each correction depends on the solution of previous ones, we can analyze how (through mechanism of transfer of coherences and transfer of populations between Zeeman sublevels) electromagnetically induced absorption is formed. We also discuss qualitative differences in the behavior (with respect to time) of certain density matrix elements for magnetic fields "inside" and "outside" electromagnetically induced absorption resonance.
3
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Laser Beam Profile Influence on Dark Hanle Resonances in Rb Vapor

61%
Krmpot A., Ćuk S., Nikolić S., Radonjić M., Grujić Z., Jelenković B.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
563-565
EN
Influence of two different laser beam profiles, the Gaussian and the Π (top hat) profile on the resonance line widths and amplitudes in the Hanle electromagnetically induced transparency was studied. The laser beam propagates through the vacuum Rb glass cell. Studies were done at D_1 line for the open ^{87}Rb: F_{g}=2 → F_{e}=1 transition. Hanle electromagnetically induced transparency was measured for the two beam profiles with the same total power and beam diameter and experimental results showed that Gaussian and the top hat profiles give different amplitudes and widths of the Hanle resonances. Resonances obtained from the top hat laser beam profile have lower amplitudes and higher line widths.
4
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Effect of Laser Light Ellipticity on Hanle Electromagnetically Induced Absorption Amplitude and Line Width

61%
Dimitrijević J., Grujić Z., Mijailović M., Arsenović D., Panić B., Jelenković B.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
841-845
EN
Using the ^2S_{1/2} F_g=2→^2P_{3/2} F_e=3 transition in ^{87}Rb, we analyzed the interaction between the arbitrarily polarized laser light and Zeeman sublevels in the Hanle configuration. We studied theoretically and confirmed experimentally that the effect of the laser light polarization on the electromagnetically induced absorption strongly depends on the laser light power. For the same atomic transition, and for single laser light power (3 mW), it was recently shown that electromagnetically induced absorption line widths increase with polarization ellipticity and that electromagnetically induced absorption amplitude has maximum for certain laser light polarization different than linear. Here, we present results for amplitudes and widths of electromagnetically induced absorption for different laser light polarizations and for the laser light power≤ 200μW. It is verified that for small laser light power maximal electromagnetically induced absorption amplitude is for the linear polarization, whereas for larger power maximum of the electromagnetically induced absorption is at higher polarization ellipticity.
5
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Zeeman Coherences Narrowing due to Ramsey Effects Induced by Thermal Motion of Rubidium Atoms

52%
Grujić Z., Mijailović M., Panić B., Minić M., Kovačević A., Obradović M., Jelenković B., Cartaleva S.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
799-803
EN
We investigated effects of spatially separated laser fields on amplitudes and widths of electromagnetically induced transparency in M-type atomic system. We have shown narrowing of the electromagnetically induced transmission resonance and therefore enhancement of medium non-linearities that can be explained by diffusion-induced Ramsey narrowing. Depending on the polarization of two laser beams, narrow probe Hanle transmission resonance changes its sign in respect of the profile obtained when the pump laser beam is off.
6
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Lateral intra-extraspinal cervical schwannomas: Partial versus total resection

52%
Stefanović I., Bošnjaković P., Kostić A., Stefanovic S., Stojanov D., Dimov D., Radisavljević M., Jelenković B.
Open Medicine
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2012
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vol. 7
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issue 1
66-72
EN
The study involved 27 lateral cervical schwannomas surgically treated in the last 40 years utilizing either partial or total resection. The study aims to compare the results of total and partial resection of spinal lateral schwannoma and to assess the values of partial resection of large lateral cervical schwannomas. We performed a retrospective analysis of 27 patients operated for lateral cervical schwannomas in the period 1971–2010, out of which 11 had partial resection. The average follow-up of the patients was 136.4 months, comparing pre- and postoperative clinical picture, time to relapse, dynamics of yearly growth of schwannomas, and the need for re-resection. The average period of preoperative complaint in lateral cervical schwannomas was 19.6 months. Unilateral cervicobrachialgia as a manifestation of radiculopathy was observed in 85% of LCSs, and, was, as a rule the first symptom of the disease. Surgical treatment of 27 patients with LCSs resulted in recovery or improvement of complaints in 80% of cases. The treatment effect did not depend on the degree of resection. Reoperation was done, on average, 16.3 years after partial resection. The residues of lateral cervical schwannomas stopped growing 15 years after partial resection and underwent cystic degeneration. Partial resection of lateral cervical schwannomas is an excellent alternative to total resection, not only for the elderly or in cases of increased surgical risk, but also as a method of choice since it is more readily available to a larger number of surgeons and associated with low percentages of surgically relevant relapses and high percentages of improvement.
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