No Arabic abstract
We present the results of a novel Mossbauer experiment in a rotating system, implemented recently in Istanbul University, which yields the coefficient k=0.69+/-0.02 within the frame of the expression for the relative energy shift between emission and absorption lines dE/E=ku2/c2. This result turned out to be in a quantitative agreement with an experiment achieved earlier on the subject matter (A.L. Kholmetskii et al. 2009 Phys. Scr. 79 065007), and once again strongly pointed to the inequality k>0.5, revealed originally in (A.L. Kholmetskii et al. 2008 Phys. Scr. 77, 035302 (2008)) via the re-analysis of Kundig experiment (W. Kundig. Phys. Rev. 129, 2371 (1963)). A possible explanation of the deviation of the coefficient k from the relativistic prediction k=0.5 is discussed.
We shortly review different attempts to interpret the results of Moessbauer rotor experiments in a rotating system and particularly we show that the latest work on this subject by J. Iovane and E. Benedetto (Ann. Phys., in press), which claims that the outcomes of these experiments can supposedly be explained via desynchronization of clocks in the rotating frame and in the laboratory frame, is inapplicable to all of the Moessbauer rotor experiments performed up to date and thus does not have any significance.
We show that a new attempt by C. Corda to once more rehash his so-called synchronization effect in order to account for the origin of the extra energy shift between emitted and absorbed radiation in Mossbauer rotor experiments (C. Corda, Int. J. Mod. Phys. D, doi: 10.1142/S0218271819501311) is yet again erroneous, just as were his previous attempts (Ann. Phys. 355, 360 (2015); Ann. Phys. 368, 258 (2016); Int. J. Mod. Phys. D 27, 1847016 (2018)). The correct approach presented herein with regards to the calculation of the energy shift between emitted and absorbed radiation in a rotating system leads to, as a matter of fact, no specific synchronization effect.
In this article we have shown that the atomic states can be engineered by tunning the coupling Rabi frequency for a system with $mathcal{N}$-type configuration. Electromagnetically induced transparency (EIT), Electromagnetically induced absorption (EIA) and Autler-Townes (AT) splitting has been observed experimentally in a four level $mathcal{N}$-type atomic vapor of $^{85}Rb$ atoms in the hyperfine levels of $D_2$ transition. It has been shown that the response of the atomic medium can be tunned from highly transparent to highly absorptive in our case. The evolution of the atomic states from the dark state |D> to the non-coupled state |NC> has been studied with the partial dressed state approach which makes the backbone of the modification of the atomic response. In addition, transient solutions in the time domain and steady state solution in the frequency domain has been studied. The population dynamics and the coherence contribution in each case has been analyzed by the time dependent solutions. The experimentally observed steady line-shape profiles has been supported by the steady state solution of optical-Bloch equations considering the Maxwell Boltzmann velocity distributions of the atoms. It has been observed that the crossover between the EIT and the AT splitting has been replaced by the interference contribution of the EIA in this $mathcal{N}$-type system.
We wish to study the extent and subparsec scale spatial structure of intervening quasar absorbers, mainly those involving neutral and molecular gas. We have selected quasar absorption systems with high spectral resolution and good S/N data, with some of their lines falling on quasar emission features. By investigating the consistency of absorption profiles seen for lines formed either against the quasar continuum source or on the much more extended emission line region (ELR), we can probe the extent and structure of the foreground absorber over the extent of the ELR (0.3-1 pc). The spatial covering analysis provides constraints on the transverse size of the absorber and thus is complementary to variability or photoionisation modelling studies. The methods we used to identify spatial covering or structure effects involve line profile fitting and curve of growth analysis.We have detected three absorbers with unambiguous non uniformity effects in neutral gas. For one extreme case, the FeI absorber at z_abs=0.45206 towards HE 0001-2340, we derive a coverage factor of the ELR of at most 0.10 and possibly very close to zero; this implies an absorber overall size no larger than 0.06 pc. For the z_abs=2.41837 CI absorber towards QSO J1439+1117, absorption is significantly stronger towards the ELR than towards the continuum source in several CI and CI* velocity components pointing to factors of about two spatial variations of their column densities and the presence of structures at the 100 au - 0.1 pc scale. The other systems with firm or possible effects can be described in terms of partial covering of the ELR, with coverage factors in the range 0.7 - 1. The overall results for cold, neutral absorbers imply a transverse extent of about five times or less the ELR size, which is consistent with other known constraints.
The rotational dynamics of particles subject to external illumination is found to produce light amplification and inelastic scattering at high rotation velocities. Light emission at frequencies shifted with respect to the incident light by twice the rotation frequency dominates over elastic scattering within a wide range of light and rotation frequencies. Remarkably, net amplification of the incident light is produced in this classical linear system via stimulated emission. Large optically-induced acceleration rates are predicted in vacuum accompanied by moderate heating of the particle, thus supporting the possibility of observing these effects under extreme rotation conditions.