4,575 research outputs found
A Quantum Key Distribution Network Through Single Mode Optical Fiber
Quantum key distribution (QKD) has been developed within the last decade that
is provably secure against arbitrary computing power, and even against quantum
computer attacks. Now there is a strong need of research to exploit this
technology in the existing communication networks. In this paper we have
presented various experimental results pertaining to QKD like Raw key rate and
Quantum bit error rate (QBER). We found these results over 25 km single mode
optical fiber. The experimental setup implemented the enhanced version of BB84
QKD protocol. Based upon the results obtained, we have presented a network
design which can be implemented for the realization of large scale QKD
networks. Furthermore, several new ideas are presented and discussed to
integrate the QKD technique in the classical communication networks.Comment: This paper has been submitted to the 2006 International Symposium on
Collaborative Technologies and Systems (CTS 2006)May 14-17, 2006, Las Vegas,
Nevada, US
On the Solution of the Number-Projected Hartree-Fock-Bogoliubov Equations
The numerical solution of the recently formulated number-projected
Hartree-Fock-Bogoliubov equations is studied in an exactly soluble
cranked-deformed shell model Hamiltonian. It is found that the solution of
these number-projected equations involve similar numerical effort as that of
bare HFB. We consider that this is a significant progress in the mean-field
studies of the quantum many-body systems. The results of the projected
calculations are shown to be in almost complete agreement with the exact
solutions of the model Hamiltonian. The phase transition obtained in the HFB
theory as a function of the rotational frequency is shown to be smeared out
with the projection.Comment: RevTeX, 11 pages, 3 figures. To be published in a special edition of
Physics of Atomic Nuclei (former Sov. J. Nucl. Phys.) dedicated to the 90th
birthday of A.B. Migda
Isovector and isoscalar superfluid phases in rotating nuclei
The subtle interplay between the two nuclear superfluids, isovector T=1 and
isoscalar T=0 phases, are investigated in an exactly soluble model. It is shown
that T=1 and T=0 pair-modes decouple in the exact calculations with the T=1
pair-energy being independent of the T=0 pair-strength and vice-versa. In the
rotating-field, the isoscalar correlations remain constant in contrast to the
well known quenching of isovector pairing. An increase of the isoscalar (J=1,
T=0) pair-field results in a delay of the bandcrossing frequency. This
behaviour is shown to be present only near the N=Z line and its experimental
confirmation would imply a strong signature for isoscalar pairing collectivity.
The solutions of the exact model are also discussed in the
Hartree-Fock-Bogoliubov approximation.Comment: 5 pages, 4 figures, submitted to PR
p-p' System with B-field, Branes at Angles and Noncommutative Geometry
We study the generic system in the presence of constant NS
2-form field. We derive properties concerning with the
noncommutativity of D-brane worldvolume, the Green functions and the spectrum
of this system. In the zero slope limit, a large number of light states appear
as the lowest excitations in appropriate cases. We are able to relate the
energies of the lowest states after the GSO projection with the configurations
of branes at angles. Through analytic continuation, the system is compared with
the branes with relative motion.Comment: 21 pages, Latex. References regarding to section 3 and 4 added. Typos
correcte
Extensions of AdS_5 x S^5 and the Plane-wave Superalgebras and Their Realization in the Tiny Graviton Matrix Theory
In this paper we consider all consistent extensions of the AdS_5 x S^5
superalgebra, psu(2,2|4), to incorporate brane charges by introducing both
bosonic and fermionic (non)central extensions. We study the Inonu-Wigner
contraction of the extended psu(2,2|4) under the Penrose limit to obtain the
most general consistent extension of the plane-wave superalgebra and compare
these extensions with the possible BPS (flat or spherical) brane configurations
in the plane-wave background. We give an explicit realization of some of these
extensions in terms of the Tiny Graviton Matrix Theory (TGMT)[hep-th/0406214]
which is the 0+1 dimensional gauge theory conjectured to describe the DLCQ of
strings on the AdS_5 x S^5 and/or the plane-wave background.Comment: 27 pages, LaTe
On the stationary vibrations of a rectangular plate subjected to stress prescribed partially at the circumference
The stationary periodical problem of a vibrating rectangular plate, stressed at a segment
while fixed elsewhere at one of its edges, is considered. Using the finite Fourier transformation, the problem
is converted to a singular integral equation that in turn can be reduced to an infinite system of algebraic
equations. The truncation of the algebraic system is justified
Building the field of health policy and systems research: framing the questions.
In the first of a series of articles addressing the current challenges and opportunities for the development of Health Policy & Systems Research (HPSR), Kabir Sheikh and colleagues lay out the main questions vexing the field
Some Immunologic Evaluations of Toxoplasmosis in Iraqi Aborted Females
Forty-eight aborted women (Iraqi Arab Muslims) at the first trimester with a serological evidence of toxoplasmosis were investigated. Two age- and ethnic-matched control groups were included: 40 aborted women due to accidental events (Control I), and 40 unmarried (virgin) women (Control II). The subjects were evaluated for the following parameters: HLA-class I antigens (A, B and Cw), blood groups, total and differential counts of leukocytes, lymphocyte subpopulations (CD3+, CD4+ and CD20+ cells), phagocytosis of heat-killed yeast (phagocytic index and NBT index), and total serum levels of immunoglobulins (IgA, IgG and IgM) and complement components (C3 and C4). The HLA-A2 and -Cw8 antigens were significantly increased in the patients, while A3 antigen was significantly decreased. Blood group phenotypes in patients and controls also showed significant variations. The total and differential counts of leukocytes showed no significant differences between patients and controls, with the exception of lymphocytes, which showed a significant decreased count in the patients compared to control II. However, the lymphocyte subpopulations showed a significant increased percentage in patients. The phagocytic index was approximated in patients and controls, while NBT index was significantly decreased. Total serum level of IgG was significantly increased in the patients, while IgA, IgM, C3 and C4 levels did not maintain such variation
On black hole temperature in Horndeski gravity
It has been observed that for black holes in certain family of Horndeski gravity theories Wald's entropy formula does not lead to the correct first law for black hole thermodynamics. For this family of Horndeski theories speeds of propagation of gravitons and photons are in general different and gravitons move on an effective metric different than the one seen by photons. We show that the temperature of the black hole should be modified from surface gravity over 2\u3c0 to include effects of this effective metric. The modified temperature, with the entropy unambiguously computed by the solution phase space method, yields the correct first law. Our results have far reaching implications for the Hawking radiation and species problem, going beyond the Horndeski theories
- …