3,914 research outputs found

    Chemical Evolution of Strongly Magnetized Quark Core in a Newborn Neutron Star

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    The chemical evolution of nascent quark matter core in a newborn compact neutron star is studied in presence of a strong magnetic field. The effective rate of strange quark production in degenerate quark matter core in presence of strong magnetic fields is obtained. The investigations show that in presence of strong magnetic fields a quark matter core becomes energetically unstable and hence a deconfinement transition to quark matter at the centre of a compact neutron star under such circumstances is not possible. The critical strength of magnetic field at the central core to make the system energetically unstable with respect to dense nuclear matter is found to be 4.4×1013\sim 4.4\times 10^{13}G. This is the typical strength at which the Landau levels for electrons are populated. The other possible phase transitions at such high density and ultra strong magnetic field environment are discussed.Comment: 18 pages, latex, eight EPS figures not included, available under request, REVTEX forma

    Quantum Cloning, Bell's Inequality and Teleportation

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    We analyze a possibility of using the two qubit output state from Buzek-Hillery quantum copying machine (not necessarily universal quantum cloning machine) as a teleportation channel. We show that there is a range of values of the machine parameter ξ\xi for which the two qubit output state is entangled and violates Bell-CHSH inequality and for a different range it remains entangled but does not violate Bell-CHSH inequality. Further we observe that for certain values of the machine parameter the two-qubit mixed state can be used as a teleportation channel. The use of the output state from the Buzek-Hillery cloning machine as a teleportation channel provides an additional appeal to the cloning machine and motivation of our present work.Comment: 7 pages and no figures, Accepted in Journal of Physics

    Electrical Conductivity at the Core of a Magnetar

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    An expression for the electrical conductivity at the core of a magnetar is derived using Boltzmann kinetic equation with the relaxation time approximation. The rates for the relevant scattering processes, e.g., electron-electron and electron-proton are evaluated in presence of strong quantizing magnetic fields using tree level diagrams. It is found that in presence of a strong quantizing magnetic field, electrical conductivity behaves like a second rank tensor. However, if the zeroth Landau levels are only occupied by the charged particles, it again behaves like a scaler of a one dimensional system.Comment: REVTEX File, 4 .eps figures (included

    R-Modes on Rapidly Rotating, Relativistic Stars: I. Do Type-I Bursts Excite Modes in the Neutron-Star Ocean?

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    During a Type-I burst, the turbulent deflagation front may excite waves in the neutron star ocean and upper atmosphere with frequencies, ω1\omega \sim 1 Hz. These waves may be observed as highly coherent flux oscillations during the burst. The frequencies of these waves changes as the upper layers of the neutron star cool which accounts for the small variation in the observed QPO frequencies. In principle several modes could be excited but the fundamental buoyant rr-mode exhibits significantly larger variability for a given excitation than all of the other modes. An analysis of modes in the burning layers themselves and the underlying ocean shows that it is unlikely these modes can account for the observed burst oscillations. On the other hand, photospheric modes which reside in a cooler portion of the neutron star atmosphere may provide an excellent explanation for the observed oscillations.Comment: 18 pages, 1 figure, substantial changes and additions to reflect version to appear in Ap

    Variation of D-region nitric-oxide density with solar activity and season at the dip equator

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    To study the solar control on electron density (N sub e) in the equatorial D region, a program was initiated with Soviet collaboration in 1979. A total of 31 rockets were launched during the high solar activity period, and 47 rockets during the low solar activity period, from Thumba to measure the N sub e profiles. Analysis of the data shows that the average values of N sub e for the high solar activity period are higher by a factor of about 2 to 3 compared to the low solar activity values. It was found that a single nitric oxide density, (NO), profile cannot reproduce all the observed N sub e profiles. An attempt was made to reproduce theoretically the observed N sub e profiles by introducing variation in (NO) for the different solar activity periods and seasons