Sajid Qamar

Precision localization of single atom using Autler–Townes microscopy

Abstract Detuning of the classical standing wave field with the atomic transition plays an important role in the characterization of the peaks present in Autler–Townes spontaneous spectrum of a three-level atom. We investigate how this detuning effects the position distribution of the atom and show that we gain a precision in position information of the single atom inside the standing wave field by introducing the detuning between the atomic transition frequency and the frequency of the driving field in the upper-level coupling case. We also show that this precision in localization of an atom is not observed in the lower-level coupling case, due to the absence of the quantum interference.

Hanbury Brown-Twiss effect and thermal light ghost imaging : A unified approach

We compare the Hanbury Brown\char21{}Twiss (HBT) and the thermal light ghost imaging schemes in both near and far fields. Both effects arise as a result of the intensity fluctuations of the thermal light and we find that the essential physics behind the two effects is the same. The difference however is that, in the ghost imaging, large number of bits information of an object needs to be treated together, whereas, in the HBT, there is only one bit information required to be obtained. In the HBT experiment far field is used for the purpose of easy detection, while in the ghost image experiment near (or not far) field is used for good quality image.

Reconstruction of the Wigner function of the Schrödinger-cat state via time-dependent Autler-Townes spectroscopy

Equivalent descriptions of the quantum state of the radiation field can be formulated in terms of the quasiprobability distributions such as P-representation, Q-representation, and the Wigner distribution function. The paper presents a physical and more realistic model for the reconstruction of the Wigner distribution function of the Schrödinger-cat state using time-dependent Autler-Townes spontaneous emission spectroscopy.

An optimized image fusion algorithm for night-time surveillance and navigation

Multi-sensor Image fusion has its effective utilization for night-time surveillance and navigation.It provides a way to merge multi-sensor nighttime imagery by combining the outputs of different imaging sensors . In this paper, we present an optimized image fusion approach comprising Structural Similarity, Principle Component Analysis and Discrete Wavelet Transform.The use of structural similarity is proposed for adjusting the quality of finally fused image. Recently developed objective image fusion qualiy evaluation technique, image quality index, is used to evaluate the performance of our fusion algorithm. Experimental results show that it performs considerably well across a variety of multi-source nighttime imaging data.

Goos-Hänchen shift of partially coherent light fields in epsilon-near-zero metamaterials.

The Goos-Hänchen (GH) shifts in the reflected light are investigated both for p and s polarized partial coherent light beams incident on epsilon-near-zero (ENZ) metamaterials. In contrary to the coherent counterparts, the magnitude of GH shift becomes non-zero for p polarized partial coherent light beam; while GH shift can be relatively large with a small degree of spatial coherence for s polarized partial coherent beam. Dependence on the beam width and the permittivity of ENZ metamaterials is also revealed for partial coherent light fields. Our results on the GH shifts provide a direction on the applications for partial coherent light sources in ENZ metamaterials.

Precision in 2D atom localization via coherent manipulation of the Raman gain process

A four-level N-type atom–field system exhibiting the Raman gain process is revisited for precision in position information of a single atom in a two-dimensional (2D) xy-plane. The atom interacts with two standing-wave fields where each standing-wave field is obtained via superposition of two orthogonal standing-wave fields, i.e., along the x and y directions, whereas a probe field is applied to observe the Raman gain process. The role of probe field detuning and phase shifts associated with the standing-wave fields in precision position information of a single atom in a 2D plane is investigated. The suggested scheme leads to enhancement in the spatial resolution in measuring the position of the atom, and a single atom localization peak in the xy-plane having a spatial resolution of the order of λ/10 is noticed.

Time-dependent Autler-Townes spectroscopy

Autler–Townes spontaneous emission spectroscopy is revisited for a time-dependent case. We report the results of spontaneous emission spectra for nonstationary scattered light signals using the definition of the time-dependent physical spectrum. This is a rare example of problems where time-dependent spectra can be calculated exactly.

Coherent control of the group velocity in a dielectric slab doped with duplicated two-level atoms

Coherent control of reflected and transmitted pulses is investigated theoretically through a slab doped with atoms in a duplicated two-level configuration. When a strong control field and a relatively weak probe field are employed, coherent control of the group velocity is achieved via changing the phase shift between control and probe fields. Furthermore, the peak values in the delay time of the reflected and transmitted pulses are also studied by varying the phase shift .

Subwavelength position measurements with running-wave driving fields

Subwavelength position measurement of quantum particles is discussed. Our setup is based on a closed-loop driving-field configuration, which enforces a sensitivity of the particle dynamics to the phases of the applied fields. Thus, running wave fields are sufficient, avoiding limitations associated with standing-wave-based localization schemes. Reversing the directions of the driving laser fields switches between different magnification levels for the position determination. This allows us to optimize the localization, and at the same time eliminates the need for additional classical measurements common to all previous localization schemes based on spatial periodicity.

Uranium spectra in the ICP

Abstract Uranium spectra have been studied by inductively coupled plasma atomic emission spectroscopy (ICP-AES). In total, 8361 uranium lines were observed in the wavelength range of 235–500 nm. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hard copy text is accompanied by a disk with data files and text files for an IBM-compatible computer. The main article discusses the scientific aspects of the subject and explains the purpose of the data files.