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

Continuous-variable entanglement in a correlated spontaneous emission laser

Journals published by the American Physical Society can be found at http://publish.aps.org/We discuss the generation and evolution of entangled light in a correlated spontaneous emission laser. The master equation for the two-mode field in a cavity is derived and solved analytically. The time-dependent characteristic function in the Wigner representation for the two-mode field is obtained. It shows that the two-mode field in the cavity evolves in a two-mode Gaussian state. The entanglement degree of the two-mode field in the cavity increases initially, then decreases, and finally vanishes as the field evolves from an initial vacuum. The period of the entanglement is extended as the intensity of the driving field is increased. It is found that the entanglement still exists even when the two-mode squeezing disappears. During the entanglement period, the intensity of the field is amplified. The entanglement for the initial field being a two-mode squeezed vacuum and the entanglement of the output field are also discussed

Teleportation of an atomic momentum state

Journals published by the American Physical Society can be found at http://publish.aps.org/In this paper, we propose a scheme for teleportating a superposition of atomic center-of-mass momentum states to a superposition of the cavity field using quantum controlled-NOT gate via atomic scattering in the Bragg regime and cavity quantum electrodynamics

Quenching of spontaneous emission through interference of incoherent pump processes

Journals published by the American Physical Society can be found at http://publish.aps.org/We investigate the steady-state spontaneous emission of a V-type three-level atom, with the coherence between the two upper levels modified and controlled via incoherent pumping to a fourth auxiliary level. The external pumping gives us an easily controllable handle in manipulating the spontaneous emission to such an extent that, under certain conditions, complete quenching of spontaneous emission is possible. We also show that even the interference between the decay channels, which is considered a key requirement in spontaneous emission quenching through quantum interference, is not essential to achieve near 100% trapping and almost complete suppression of spontaneous emission. Thus we provide a scheme for spontaneous emission quenching which can be easily realized experimentally

Condensation of N bosons. II. Nonequilibrium analysis of an ideal Bose gas and the laser phase-transition analogy

Journals published by the American Physical Society can be found at http://publish.aps.org/A nonequilibrium approach to the dynamics and statistics of the condensate of an ideal N-atom Bose gas cooling via interaction with a thermal reservoir using the canonical ensemble is developed. We derive simple analytical expressions for the canonical partition function and equilibrium distribution of the number of atoms in the ground state of a trap under different approximations, and compare them with exact numerical results. The N-particle constraint associated with the canonical ensemble is usually a burden. In the words of Kittel, "in the investigation of the Bose-Einstein... laws it is very inconvenient to impose the restriction that the number of particles in the subsystem shall be held constant." But in the present approach, based on the analogy between a second-order phase transition and laser threshold behavior, the N-particle constraint makes the problem easier. We emphasize that the present work provides another example of a case in which equilibrium (detailed balance) solutions to nonequilibrium equations of motion provide a useful supplementary approach to conventional statistical mechanics. We also discuss some dynamical and mesoscopic aspects of Bose-Einstein condensation. The conclusion is that the present analytical (but approximate) results, based on a nonequilibrium approach, are in excellent agreement with exact (but numerical) results. The present analysis has much in common with the quantum theory of the laser

Two-time intensity correlation in a driven three-level system

Journals published by the American Physical Society can be found at http://publish.aps.org/We examine the various two-time fluorescence intensity correlations emitted by a driven three-level atom in a cascade configuration. For a strongly driven atom, the two intensity autocorrelation functions, one from the upper transition, the other from the lower transition, exhibit different behaviors. In addition to the an oscillation similar to the two-level intensity correlation we find an additional oscillation for the upper transition only. This is shown to be due to the spontaneous decay between the lower transition levels

Exacerbation of N-nitrosodiethylamine Induced Hepatotoxicity and DNA Damage in Mice Exposed to Chronic Unpredictable Stress

Psychological stress contributes to increased susceptibility to a number of diseases including cancer. The present study was designed to assess the effect of chronic unpredictable stress on N-nitrosodiethylamine induced liver toxicity in terms of in vivo antioxidant status and DNA damage in Swiss albino mice. The animals used in this study were randomized into different groups based on the treatment with N-nitrosodiethylamine or chronic unpredictable stress alone and post-stress administration of N-nitrosodiethylamine. The mice were sacrificed after 12 weeks of treatment, and the status of major enzymatic and non-enzymatic antioxidants, liver function markers, lipid peroxidation and the extent of DNA damage were determined in circulation and liver tissues of all the groups. The N-nitrosodiethylamine treated group showed significantly compromised levels of the antioxidant enzymes, lipid peroxidation, and the liver function markers with enhanced DNA damage as compared to chronic unpredictable stress or control groups. A similar but less typical pattern observed in the chronic unpredictable stress treated mice. All the measured biochemical parameters were significantly altered in the group treated with the combination of chronic unpredictable stress and N-nitrosodiethylamine when compared to controls, or chronic unpredictable stress alone and/or N-nitrosodiethylamine alone treated groups. Thus, exposure to continuous, unpredictable stress conditions even in general life may significantly enhance the hepatotoxic potential of N-nitrosodiethylamine through an increase in the oxidative stress and DNA damage

Optically controlled delays for broadband pulses

Journals published by the American Physical Society can be found at http://publish.aps.org/We propose a scheme that provides large controllable delays for broadband optical pulses. The system is based on the steep dispersion of a coherently driven medium, in which the narrow electromagnetically induced transparency (EIT) band is overcome by using spatial and temporal processing