777 research outputs found
Security of the Bennett 1992 quantum-key distribution against individual attack over a realistic channel
The security of two-state quantum key distribution against individual attack
is estimated when the channel has losses and noises. We assume that Alice and
Bob use two nonorthogonal single-photon polarization states. To make our
analysis simple, we propose a modified B92 protocol in which Alice and Bob make
use of inconclusive results and Bob performs a kind of symmetrization of
received states. Using this protocol, Alice and Bob can estimate Eve's
information gain as a function of a few parameters which reflect the
imperfections of devices or Eve's disturbance. In some parameter regions, Eve's
maximum information gain shows counter-intuitive behavior, namely, it decreases
as the amount of disturbances increases. For a small noise rate Eve can extract
perfect information in the case where the angle between Alice's two states is
small or large, while she cannot extract perfect information for intermediate
angles. We also estimate the secret key gain which is the net growth of the
secret key per one pulse. We show the region where the modified B92 protocol
over a realistic channel is secure against individual attack.Comment: 16 pages, 15 figure
Measurement of the inclusive branching fraction tau- ---> TAU-neutrino pi- pi0 + neutral meson(s)
Recommended from our members
Spring-mass behavioural adaptations to acute changes in prosthetic blade stiffness during submaximal running in unilateral transtibial prosthesis users
YesBackground: Individuals with lower-limb amputation can use running specific prostheses (RSP) that store and
then return elastic energy during stance. However, it is unclear whether varying the stiffness category of the
same RSP affects spring-mass behaviour during self-selected, submaximal speed running in individuals with
unilateral transtibial amputation.
Research question: The current study investigates how varying RSP stiffness affects limb stiffness, running performance,
and associated joint kinetics in individuals with a unilateral transtibial amputation.
Methods: Kinematic and ground reaction force data were collected from eight males with unilateral transtibial
amputation who ran at self-selected submaximal speeds along a 15 m runway in three RSP stiffness conditions;
recommended habitual stiffness (HAB) and, following 10-minutes of familiarisation, stiffness categories above
(+1) and below (-1) the HAB. Stance-phase centre of mass velocity, contact time, limb stiffness’ and joint/RSP
work were computed for each limb across RSP stiffness conditions.
Results: With increased RSP stiffness, prosthetic limb stiffness increased, whilst intact limb stiffness decreased
slightly (
Screening of qubit from zero-temperature reservoir
We suggest an application of dynamical Zeno effect to isolate a qubit in the
quantum memory unit against decoherence caused by coupling with the reservoir
having zero temperature. The method is based on using an auxiliary casing
system that mediate the qubit-reservoir interaction and is simultaneously
frequently erased to ground state. This screening procedure can be implemented
in the cavity QED experiments to store the atomic and photonic qubit states.Comment: 4 pages, 5 figure
SMT-based Model Checking for Recursive Programs
We present an SMT-based symbolic model checking algorithm for safety
verification of recursive programs. The algorithm is modular and analyzes
procedures individually. Unlike other SMT-based approaches, it maintains both
"over-" and "under-approximations" of procedure summaries. Under-approximations
are used to analyze procedure calls without inlining. Over-approximations are
used to block infeasible counterexamples and detect convergence to a proof. We
show that for programs and properties over a decidable theory, the algorithm is
guaranteed to find a counterexample, if one exists. However, efficiency depends
on an oracle for quantifier elimination (QE). For Boolean Programs, the
algorithm is a polynomial decision procedure, matching the worst-case bounds of
the best BDD-based algorithms. For Linear Arithmetic (integers and rationals),
we give an efficient instantiation of the algorithm by applying QE "lazily". We
use existing interpolation techniques to over-approximate QE and introduce
"Model Based Projection" to under-approximate QE. Empirical evaluation on
SV-COMP benchmarks shows that our algorithm improves significantly on the
state-of-the-art.Comment: originally published as part of the proceedings of CAV 2014; fixed
typos, better wording at some place
Soft-core baryon-baryon potentials for the complete baryon octet
SU(3) symmetry relations on the recently constructed hyperon-nucleon
potentials are used to develop potential models for all possible baryon-baryon
interaction channels. The main focus is on the interaction channels with total
strangeness S=-2, -3, and -4, for which no experimental data exist yet. The
potential models for these channels are based on SU(3) extensions of potential
models for the S=0 and S=-1 sectors, which are fitted to experimental data.
Although the SU(3) symmetry is not taken to be exact, the S=0 and S=-1 sectors
still provide the necessary constraints to fix all free parameters. The
potentials for the S=-2, -3, and -4 sectors, therefore, do not contain any
additional free parameters, which makes them the first models of this kind.
Various properties of the potentials are illustrated by giving results for
scattering lengths, bound states, and total cross sections.Comment: 22 pages RevTex, 6 postscript figure
GUI Matlab para o cálculo de funções de Bessel usando frações continuadas
[EN] Higher order Bessel functions are prevalent in physics and engineering and there exist different methods to evaluate them quickly and efficiently. Two of these methods are Miller's algorithm and the continued fractions algorithm. Miller's algorithm uses arbitrary starting values and normalization constants to evaluate Bessel functions. The continued fractions algorithm directly computes each value, keeping the error as small as possible. Both methods respect the stability of the Bessel function recurrence relations. Here we outline both methods and explain why the continued fractions algorithm is more efficient. The goal of this paper is both (1) to introduce the continued fractions algorithm to physics and engineering students and (2) to present a MATLAB GUI (Graphic User Interface) where this method has been used for computing the Semi-integer Bessel Functions and their zeros.[PT] Funções de Bessel de ordem mais alta sĂŁo recorrentes em fĂsica e nas engenharias, sendo que há diferentes mĂ©todos para calculá-las de maneira rápida e eficiente. Dois destes mĂ©todos sĂŁo o algoritmo de Miller e o algoritmo de frações continuadas. O primeiro faz uso de valores iniciais e constantes de normalização arbitrários, enquanto o segundo o faz calculando cada valor diretamente, minimizando tanto quanto possĂvel o erro. Ambos respeitam a estabilidade das relações de recorrĂŞncia das funções de Bessel. Neste trabalho descrevemos ambos os mĂ©todos e explicamos a razĂŁo pela qual o algoritmo das frações continuadas Ă© mais eficiente. O objetivo do artigo Ă© (1) introduzir o algoritmo de frações continuadas para estudantes de fĂsica e das engenharias e (2) apresentar um GUI (Graphic User Interface) em Matlab no qual este mĂ©todo foi utilizado para calcular funções de Bessel semi-inteiras e seus zeros.The authors wish to thank the financial support received from the Universidad PolitĂ©cnica de Valencia under grant PAID-06-09-2734, from the Ministerio de Ciencia e InnovaciĂłn through grant ENE2008-00599 and specially from the Generalitat Valenciana under grant reference 3012/2009.Hernandez Vargas, E.; Commeford, K.; PĂ©rez Quiles, MJ. (2011). MATLAB GUI for computing Bessel functions using continued fractions algorithm. Revista Brasileira de Ensino de FĂsica. 33(1):1303-1311. https://doi.org/10.1590/S1806-11172011000100003S13031311331Giladi, E. (2007). Asymptotically derived boundary elements for the Helmholtz equation in high frequencies. Journal of Computational and Applied Mathematics, 198(1), 52-74. doi:10.1016/j.cam.2005.11.024Havemann, S., & Baran, A. J. (2004). Calculation of the phase matrix elements of elongated hexagonal ice columns using the T-matrix method. Journal of Quantitative Spectroscopy and Radiative Transfer, 89(1-4), 87-96. doi:10.1016/j.jqsrt.2004.05.014Segura, J., Fernández de CĂłrdoba, P., & Ratis, Y. L. (1997). A code to evaluate modified bessel functions based on thecontinued fraction method. Computer Physics Communications, 105(2-3), 263-272. doi:10.1016/s0010-4655(97)00069-6Bastardo, J. L., Abraham Ibrahim, S., Fernández de CĂłrdoba, P., UrchueguĂa Schölzel, J. F., & Ratis, Y. L. (2005). Evaluation of Fresnel integrals based on the continued fractions method. Applied Mathematics Letters, 18(1), 23-28. doi:10.1016/j.aml.2003.12.009Barnett, A. R., Feng, D. H., Steed, J. W., & Goldfarb, L. J. B. (1974). Coulomb wave functions for all real η and ϱ. Computer Physics Communications, 8(5), 377-395. doi:10.1016/0010-4655(74)90013-
What Attracts Men Who Batter to Their Partners? An Exploratory Study
Men who batter, because of particular personality traits and sense of entitlement,
may select partners whom they perceive will be dependent on them,
meet their emotional needs, or be “objects” of physical attractiveness. During
treatment intake, 181 offenders responded to the question, “What attracted
you to her (your partner)?” We explored whether men who mentioned their
own needs or her physical traits would engage in more frequent and severe
violence and would have specific forms of personality disorder dimensions or
personality traits. Six categories of attraction, including “her physical traits”
and “his needs,” were derived from the men’s responses. The results showed
that men who focused on their partners’ physical attractiveness were more
likely to be violent after treatment. Men who cited their own needs for their
attraction had higher scores on borderline personality, alcohol abuse, and
psychotic thinking and lower scores on compulsive-conformingPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89970/1/Saunders-Kurko-Barlow-Crane 2011 What Attracts Men Who Batter to Their Partners JIV.pd
Expansion for Excited Baryons
We derive consistency conditions which constrain the possible form of the
strong couplings of the excited baryons to the pions. The consistency
conditions follow from requiring the pion-excited baryon scattering amplitudes
to satisfy the large-N_c Witten counting rules and are analogous to consistency
conditions used by Dashen, Jenkins and Manohar and others for s-wave baryons.
The consistency conditions are explicitly solved, giving the most general
allowed form of the strong vertices for excited baryons in the large-N_c limit.
We show that the solutions to the large-N_c consistency conditions coincide
with the predictions of the nonrelativistic quark model for these states,
extending the results previously obtained for the s-wave baryons. The 1/N_c
corrections to these predictions are studied in the quark model with arbitrary
number of colors N_c.Comment: 56 pages, REVTeX; one new Appendix added containing a discussion of
the results in the language of quark operator
The Stern-Gerlach Experiment Revisited
The Stern-Gerlach-Experiment (SGE) of 1922 is a seminal benchmark experiment
of quantum physics providing evidence for several fundamental properties of
quantum systems. Based on today's knowledge we illustrate the different
benchmark results of the SGE for the development of modern quantum physics and
chemistry.
The SGE provided the first direct experimental evidence for angular momentum
quantization in the quantum world and thus also for the existence of
directional quantization of all angular momenta in the process of measurement.
It measured for the first time a ground state property of an atom, it produced
for the first time a `spin-polarized' atomic beam, it almost revealed the
electron spin. The SGE was the first fully successful molecular beam experiment
with high momentum-resolution by beam measurements in vacuum. This technique
provided a new kinematic microscope with which inner atomic or nuclear
properties could be investigated.
The original SGE is described together with early attempts by Einstein,
Ehrenfest, Heisenberg, and others to understand directional quantization in the
SGE. Heisenberg's and Einstein's proposals of an improved multi-stage SGE are
presented. The first realization of these proposals by Stern, Phipps, Frisch
and Segr\`e is described. The set-up suggested by Einstein can be considered an
anticipation of a Rabi-apparatus. Recent theoretical work is mentioned in which
the directional quantization process and possible interference effects of the
two different spin states are investigated.
In full agreement with the results of the new quantum theory directional
quantization appears as a general and universal feature of quantum
measurements. One experimental example for such directional quantization in
scattering processes is shown. Last not least, the early history of the
`almost' discovery of the electron spin in the SGE is revisited.Comment: 50pp, 17 fig
- …