Subwavelength atom localization via amplitude and phase control of the absorption spectrum

We propose a scheme for subwavelength localization of an atom conditioned upon the absorption of a weak probe field at a particular frequency. Manipulating atom-field interaction on a certain transition by applying drive fields on nearby coupled transitions leads to interesting effects in the absorption spectrum of the weak probe field. We exploit this fact and employ a four-level system with three driving fields and a weak probe field, where one of the drive fields is a standing-wave field of a cavity. We show that the position of an atom along this standing wave is determined when probe field absorption is measured. We find that absorption of the weak probe field at a certain frequency leads to subwavelength localization of the atom in either of the two half-wavelength regions of the cavity field by appropriate choice of the system parameters. We term this result as sub-half-wavelength localization to contrast it with the usual atom localization result of four peaks spread over one wavelength of the standing wave. We observe two localization peaks in either of the two half-wavelength regions along the cavity axis.Comment: Accepted for publication to Physical Review

Effect of Substrate Temperature on Growth Bi1.6Pb0.4Sr2Ca2Cu2.4 Zn0.6O10 Thin Films Prepared by Pulsed Laser Deposition

AbstractBi1.6Pb0.4Sr2Ca2Cu2.4Zn0.6O10 superconducting pellet was prepared by solid state reaction. The epitaxial growth of Bi1.6Pb0.4Sr2Ca2Cu2.4Zn0.6O10 films has been realized on Si (111) by pulse laser deposition (PLD) using Nd: YAG laser with 532nm, pulse duration of about 7 nsec and a current density (0.4 – 8) J/cm2, at different substrate temperature 300, 320, 350 and 400°C. All samples annealed at 820°C in vacuum furnace employing oxygen atmosphere with flow rate 2 lit/min and heating rate 15°C/min. The structure and morphology of the prepared samples was obtained by using x-ray diffractometer (XRD) and atomic force microscopy (AFM). The lattice constants of thin films samples were calculated using inter planer distance and Miller indices of the strong peaks in the XRD patterns. It has been observed that the enhancement of the transition temperature (Tc) for obtained films increase with increase of substrate temperature (Ts). The increase in Tc with the enhancement of substrate temperature could be explained to increasing the mobility of clusters and subsequently enhance the critical temperature

Efficiency enhancement of photovoltaic performance of quasi-solid state dye sensitized solar cell with TPAI and KI binary iodide salt mixture

Quasi-solid-state dye-sensitized solar cells have drawn the attention of scientists and technologists as a potential candidate to supplement future energy needs. The conduction of iodide ions in quasi-solid-state polymer electrolytes and the performance of dye sensitized solar cells (DSSCs) containing such electrolytes can be enhanced by incorporating iodides having appropriate cations. Gel-type electrolytes, were prepared by solution cast technique, based on PVP-co-VAc + PMMA host polymers and mixture of salts Potassium iodide (KI) and tetrapropyl ammonium iodide (TPAI) salts have been used to provide the conducting ions. The salt composition in the binary mixture was varied in order to optimize the performance of solar cells. The electrochemical impedance spectroscopy (EIS) measurements showed that the electrolyte (C6) which contain (KI%25: 5%TPAI) have highest conductivity S/cm at 298 K. The DSSCs with TPAI or KI as the only iodide salt showed the efficiencies 4.136%and 2.532 %, respectively, under AM 1.5(1000 Wm-2) illumination  while the DSSC with mixed cations with (TPAI25%:KI5%) molar ratio shows the  efficiency of 3.179%. Keywords: Binary Iodide, Gel Polymer Electrolyte, Dye-Sensitized Solar Cells, Electrochemical Impedance Spectroscopy

Preparation and Characterization of Poly(1-vinylpyrroli done-co-vinyl acetate)/Poly(methyl methacrylate) Polymer Electrolyte based on TPAI and KI

Polymer electrolytes are promising materials for electrochemical device applications, such as , high energy density rechargeable batteries, supercapacitors, fuel cells, electrochromic displays, etc. Polymer blend electrolytes based on (PVP-co-VAc) and ( PMMA) with different weight ratio of Tetra propyl ammonium iodide (TPAI) and Potassium iodide (KI),  salts using DMSO as solvent. The gel electrolytes were  prepared by solution cast technique. More details can be found in the full paper. Keywords: Gel electrolyte ,Electrochemical Impedance Spectroscopy , Poly(1-vinylpyrrolidone-co- vinyl acetate), poly(methyl meth acryl ate), FTIR

Role of noise operators on two-photon correlations in an extended coherent Raman medium

Journals published by the American Physical Society can be found at http://publish.aps.org/An extended medium driven in a double Raman configuration generates Stokes and anti-Stokes fields that are described by coupled parametric oscillator equations with solutions that depend on input boundary operators and quantum noise operators. We identify the conditions where the boundary operators can be the substitute to the noise operators for describing two-photon cross correlation in forward and backward geometries. These conditions include short sample and small decoherence between ground states gamma(bc), and they are fulfilled by the spontaneous Raman electromagnetic induced transparency scheme (weak pump with large detuning). We verify the correspondence between the results from boundary and noise operators analytically and show that the correlation due to the boundary operators is typically smaller than that due to the noise operators. In general the noise operators are required to obtain the correct correlation, especially when the control laser field is weak and gamma(bc) is finite. Explanations for the findings are given based on the physics represented by the boundary operators and noise operators. Similar conclusions are obtained for the Stokes and anti-Stokes intensities

Effects of a Training Module on Omani Teachers' Awareness of Gifted Students with Learning Disabilities

The COVID-19 pandemic has led to the use of online and e-learning in Omani general and higher education institutions. Consequently, the pandemic imposed contemporary technological challenges when considering training programs for Omani teachers. This research seeks to record proactive steps, at the Omani and Arab levels, to examine the effectiveness of online, in-service teacher training programs. In addition, this research seeks to explore the effects of online training modules on teachers' knowledge of Gifted Students with Learning Disabilities (GSLD). In other words, the research aims to examine the effects of a training module on Omani teachers’ awareness of GSLD. According to a convenience sampling method, a total of 60 Omani teachers participated in the research. Participants were teachers of students with Learning Disabilities (LD) at the resource room program in the Muscat Governate, in the Sultanate of Oman. They were distributed equally into two groups: control (n=30), and experimental (n=30). Following the development of a Self-Awareness Scale (SAS) and the training program module, the SAS was administered to both groups as a pre-test and a post-test. The teachers in the experimental group received a two-week online training module to improve their awareness of GSLD. Results indicated that there were significant differences in the post-test of the SAS in favor of teachers in the experimental group

Contemporary and Technology Based Assessment and Feedback for Student Enhanced Learning: A Case Study of Mechanical Engineering Department at Middle East College

Assessment is an important part to identify the strengths and weaknesses of student learning. Various approaches for module delivery have been implemented, emphasizing the value of student participation and their role in the educational process. This provides an excellent strategy to evaluate students over time and improve their performances. In this study, performance-based assessment as a modern form of assessment presented and discussed. Students' work was gathered in portfolios (Microsoft OneNote) so that their performance, effort, and progress could be monitored and tracked along with the task requirements. Module delivery strategy as a case study is also presented accompanied with the assessment and feedback methods. Additionally, the significance of incorporating students in the feedback process, increasing their capacity to appraise the quality of their own and their peers' work, and fostering their capacity to conduct self-evaluations and develop into independent learners were all covered in detail. The study shows that digitalize written comments to facilitate the feedback process particularly in case of high number of students, with specific and clear criteria will help to give the right feedback at the right time. Furthermore, conducting discussion sessions to get peer feedback and reflection indicated that the understanding of students on the given feedback was improved

Coherence-induced entanglement

Journals published by the American Physical Society can be found at http://publish.aps.org/We show how atomic coherence can lead to entanglement between two thermal fields at a temperature T. We first show that the passage of a three-level atom in V configuration without coherence cannot create entanglement. However, if the excited states are driven by a microwave field, the resulting atomic coherence can lead to entanglement between the thermal fields. We show that, no matter how high the temperature of the fields is, the thermal fields can always be entangled in the presence of atomic coherence

Tunable phase control for subluminal to superluminal light propagation

Journals published by the American Physical Society can be found at http://publish.aps.org/We demonstrate tunable control of the group velocity of a weak probe pulse from subluminal to superluminal. The model is an extended Lambda-type system with two extra control fields and an extra energy level. Phase variation of one of the control fields imparts the tunability in the group velocity along with other interesting spectral behavior in the absorption spectrum