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1.
I. M. Herbauts S. Bettelli H. Hübel M. Peev 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):395-406
Some MIT researchers [Phys. Rev. A
75, 042327 (2007)] have recently claimed that
their implementation of the Slutsky-Brandt attack [Phys. Rev. A
57, 2383 (1998); Phys. Rev. A 71, 042312 (2005)] to
the BB84 quantum-key-distribution (QKD) protocol puts the security of this
protocol “to the test” by simulating “the most powerful
individual-photon attack” [Phys. Rev. A 73, 012315
(2006)].
A related unfortunate news feature by a
scientific journal [G. Brumfiel, Quantum cryptography is hacked, News @ Nature (april 2007); Nature 447, 372 (2007)]
has spurred some concern in the QKD community and among the general public
by misinterpreting the implications of this work. The present article
proves the existence of a stronger individual attack on QKD protocols with
encrypted error correction, for which tight bounds are shown, and clarifies
why the claims of the news feature incorrectly suggest a contradiction with
the established “old-style” theory of BB84 individual attacks.
The full implementation of a quantum cryptographic protocol includes a
reconciliation and a privacy-amplification stage, whose choice alters in
general both the maximum extractable secret and the optimal eavesdropping
attack. The authors of [Phys. Rev. A
75, 042327 (2007)] are concerned only with the error-free
part of the so-called sifted string, and do not consider faulty bits,
which, in the version of their protocol, are discarded. When using the
provably superior reconciliation approach of encrypted error correction
(instead of error discard), the Slutsky-Brandt attack is no more optimal
and does not “threaten” the security bound derived by Lütkenhaus [Phys. Rev. A 59, 3301 (1999)].
It is shown that the method of Slutsky and collaborators [Phys. Rev. A
57, 2383 (1998)] can
be adapted to reconciliation with error correction, and that the optimal
entangling probe can be explicitly found. Moreover, this attack fills
Lütkenhaus bound, proving that it is tight (a fact which was not
previously known). 相似文献
2.
N. Destainville 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(1):119-123
We perform Transition matrix Monte Carlo simulations to evaluate the
entropy of rhombus tilings with fixed polygonal boundaries and
2D-fold rotational symmetry. We estimate the large-size limit of
this entropy for D=4 to 10. We confirm analytic predictions of
[N. Destainville et al., J. Stat. Phys. 120, 799
(2005) and M. Widom et al., J. Stat. Phys. 120, 837
(2005)], in particular that the large size and large D limits
commute, and that entropy becomes insensible to size, phason strain
and boundary conditions at large D. We are able to infer finite
D and finite size scalings of entropy. We also show that
phason elastic constants can be estimated for any D by measuring the
relevant perpendicular space fluctuations. 相似文献
3.
A theoretical explanation is given for the “unexpected” behavior recently observed in the radiation spectrum of ultrarelativistic
electrons in a thin layer of matter in an experimental investigation of the Landau-Pomeranchuk-Migdal effect at SLAC [S. R.
Klein et al., Preprint SLAC-6378, Stanford (1993); P. L. Anthony et al., Phys. Rev. Lett. 75, 1949 (1995)].
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 11, 837–840 (10 June 1996) 相似文献
4.
5.
A remarkable theorem by Clifton et al [Found Phys. 33(11), 1561–1591 (2003)] (CBH) characterizes quantum theory in terms of information-theoretic principles. According to Bub [Stud. Hist. Phil. Mod. Phys. 35 B, 241–266 (2004); Found. Phys. 35(4), 541–560 (2005)] the philosophical significance of the theorem is that quantum theory should be regarded as a “principle” theory about (quantum) information rather than a “constructive” theory about the dynamics of quantum systems. Here we criticize Bub’s principle approach arguing that if the mathematical formalism of quantum mechanics remains intact then there is no escape route from solving the measurement problem by constructive theories. We further propose a (Wigner-type) thought experiment that we argue demonstrates that quantum mechanics on the information-theoretic approach is incomplete. 相似文献
6.
A model is developed for describing phason defects in quasicrystals in the form of dilation filaments. This model is used
to calculate the energy of edge dislocations in quasicrystals including the interaction of this type of dislocation with its
“intrinsic” phason defects and with the equilibrium phason defects present in a quasicrystal. It is shown that the contribution
of “intrinsic” phason defects to the total energy of an edge dislocation in a quasicrystal is substantial.
Fiz. Tverd. Tela (St. Petersburg) 39, 2003–2007 (November 1997) 相似文献
7.
N. Bazunova 《Czechoslovak Journal of Physics》2002,52(11):1181-1185
In this work, we construct the de Rham complex with the differential operator d satisfying theQ-Leibniz rule, whereQ is a complex number, and the condition d3=0 (ternary differential) on theh-deformed quantum plane in dimension two following the general formalism elaborated in [Bazunova et al.: Czech. J. Phys.51 (2001) 1226]. Then we construct the de Rham complex on the group SL
h
(2) which preserves theh-deformed quantum plane by the differentiation of RTT-relations, and, introducing the Maurer-Cartan forms, get an analog of
the Maurer-Cartan equation.
Presented at the 11th Colloquium “Quantum Groups and Integrable Systems”, Prague, 20–22 June 2002. 相似文献
8.
J.C. Lasjaunias P. Monceau D. Starešinić K. Biljaković 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(2):187-190
Eur. Phys. J. B 24, 315 (2001) In our Reply to the Comment [#!1!#] we refute the “straightforward” interpretation of the excess low-temperature
specific heat, Cp, contribution we have measured in our study of CDW systems K0.3MoO3 and (TaSe4)2I [#!2!#] as originating solely from normal phonon modes. The specific sensitivity of the bump in C
p
/
T
3
at low temperatures to the impurity content is consistent with the increased value of the phason pinning gap while the dispersion
of normal phonons remains unaffected. We ascribe at least this part of the anomaly to the phason contribution. As stated in
reference [3] that the phonon density of states extracted from neutron scattering measurements is the least reliable in this
energy range (<0.5 meV), we conclude that Cp measurements are more accurate for detecting the phason contribution.
Received 17 April 2002 Published online 19 July 2002 相似文献
9.
B. Audoin M. Perton N. Chigarev C. Rossignol 《The European physical journal. Special topics》2008,153(1):235-237
Investigation of thin metallic film properties by means
of picosecond ultrasonics [C. Thomsen et al., Phys. Rev. Lett. 53, 989 (1984)] has been under the scope of several studies.
Generation of longitudinal and shear waves [T. Pézeril et al., Phys. Rev. B 73, 132301 (2006); O. Matsuda et al., Phys. Rev. Lett. 93, 095501 (2004)] with a wave vector normal
to the film free surface has been demonstrated. Such measurements cannot
provide complete information about properties of anisotropic films. Extreme
focusing of a laser pump beam (≈0.5 μm) on the sample surface
has recently allowed us to provide evidence of picosecond acoustic
diffraction in thin metallic films (≈1 μm) [C. Rossignol et al., Phys. Rev. Lett. 94, 166106 (2005)]. The resulting
longitudinal and shear wavefronts propagate at group velocity through the
bulk of the film. To interpret the received signals, source directivity
diagrams are calculated taking into account material anisotropy, optical
penetration, and laser beam width on the sample surface. It is shown that
acoustic diffraction increases with optical penetration, so competing with
the increasing of directivity caused by beam width. Reflection with mode
conversion at the film-substrate interface is discussed. 相似文献
10.
We compute the dynamical structure factor S(q,τ) of an elastic medium where force dipoles appear at random in space and in time, due to “micro-collapses” of the structure.
Various regimes are found, depending on the wave vector q and the collapse time θ. In an early time regime, the logarithm of the structure factor behaves as (qτ)3/2, as predicted in (L. Cipelletti et al., Phys. Rev Lett. 84, 2275 (2000)) using heuristic arguments. However, in an intermediate-time regime we rather obtain a (qτ)5/4 behaviour. Finally, the asymptotic long-time regime is found to behave as q
3/2τ. We also give a plausible scenario for aging, in terms of a strain-dependent energy barrier for micro-collapses. The relaxation
time is found to grow with the age tw, quasi-exponentially at first, and then as t
w
4/5 with logarithmic corrections.
Received 15 April 2002 相似文献
11.
J. P. Santos F. Parente 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):339-350
Total ionization cross sections of neutral phosphorus, arsenic,
antimony, and bismuth atoms by electron impact are reported and
compared to the only available experimental results by Freund et al. [Phys. Rev. A 41, 3575 (1990)]. These calculations take into account the possibilities that some
target atoms used in the experiments were in metastable states close
to the ground state, the excitation-autoionization of nsnp4
excited states may be substantial, and the ions produced in
experiments may be in excited, low-lying metastable states. The cross sections for direct ionization calculations are based
on
the BEB model by Kim and Rudd [Phys. Rev. A 50, 3954 (1994)].
Plane-wave Born cross sections scaled by the method developed by Kim
[Phys. Rev. A 64, 3954 032713 (2001)] are used to determine the
contributions from excitation-autoionization. The combination of the BEB model and the scaled Born cross sections
is in agreement with the experimental data by Freund et al. These theoretical data are useful to experimentalists and can
be
used to complete data tables needed for plasma or astrophysical
studies. 相似文献
12.
Detecting and quantifying temporal correlations in stochastic resonance via information theory measures 总被引:1,自引:0,他引:1
O. A. Rosso C. Masoller 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):37-43
We show that Information Theory quantifiers are suitable tools for detecting and for quantifying noise-induced temporal correlations
in stochastic resonance phenomena. We use the Bandt & Pompe (BP) method [Phys. Rev. Lett. 88, 174102 (2002)] to define a probability distribution, P, that fully characterizes temporal correlations. The BP method is
based on a comparison of neighboring values, and here is applied to the temporal sequence of residence-time intervals generated
by the paradigmatic model of a Brownian particle in a sinusoidally modulated bistable potential. The probability distribution
P generated via the BP method has associated a normalized Shannon entropy, H[P], and a statistical complexity measure, C[P],
which is defined as proposed by Rosso et al. [Phys. Rev. Lett. 99, 154102 (2007)]. The statistical complexity quantifies not only randomness but also the presence of correlational structures,
the two extreme circumstances of maximum knowledge (“perfect order") and maximum ignorance (“complete randomness") being regarded
an “trivial", and in consequence, having complexity C = 0. We show that both, H and C, display resonant features as a function
of the noise intensity, i.e., for an optimal level of noise the entropy displays a minimum and the complexity, a maximum.
This resonant behavior indicates noise-enhanced temporal correlations in the sequence of residence-time intervals. The methodology
proposed here has great potential for the precise detection of subtle signatures of noise-induced temporal correlations in
real-world complex signals. 相似文献
13.
E. V. Tkalya 《JETP Letters》1999,70(6):371-374
A new nonradiative decay channel for the anomalously low-lying isomeric level 3/2+ (3.5±1.0 eV) of the 229Th nucleus in a metal via the conduction electrons is examined. The lifetime of the isomer in a metal is calculated. An explanation
is given for the experimental results of S. B. Utter et al., Phys. Rev. Lett. 82, 505 (1999), where the optical radiation spectrum of the indicated isomer was investigated.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 6, 367–370 (25 September 1999) 相似文献
14.
Andrei Khrennikov 《Journal of Russian Laser Research》2008,29(2):101-113
Our aim is to understand the role of implicit assumptions which has been used by Einstein, Podolsky, and Rosen (EPR) in their
famous article [Phys. Rev., 47, 777 (1935)] devoted to the so-called EPR paradox. We found that the projection postulate plays a crucial role in the EPR
argument. It seems that EPR made a mistake in this paper — the projection postulate was applied not in its original form (as
it has been formulated in von Neumann's book [Mathematical Foundations of Quantum mechanics, Princeton University Press (1955)] but in the form which was later formalized as Lüders' postulate [Ann. Phys., Lpz. 8, 322 (1951)]. Von Neumann's postulate was crucially modified by extending it to observables with degenerate spectra. This
modification is the real source of “quantum nonlocality.” The use of the original von Neumann postulate eliminates this problem
— instead of (an action at a distance)-nonlocality, we obtain a classical measurement nonlocality, which is related to the
synchronization of two measurements (produced on the two parts of a composite system). If one uses correctly von Neumann's
projection postulate, no “elements of reality” can be assigned to entangled systems.
Talk presented at the oral issue of J. Russ. Laser Res. dedicated to the memory of Professor Vladimir A. Isakov, Professor
Alexander S. Shumovsky, and Professor Andrei V. Vinogradov held in Moscow February 21–22, 2008. 相似文献
15.
V. Tonchev B. Ranguelov H. Omi A. Pimpinelli 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(4):539-546
We recently introduced a novel model of step flow crystal growth – the so-called “C+–C-” model [B. Ranguelov et al., C.R. Acad. Bulgare Sci. 60, 389 (2007)]. In this paper we aim to develop a complete picture of the model’s behaviour in the framework of the notion
of universality classes. The basic assumption of the model is that the reference (“equilibrium”) densities used to compute
the supersaturation might be different on either side of a step, so CL/CR ≠ 1 (L/R stands for left/right in a step train descending from left to right), and that this will eventually cause destabilization
of the regular step train. Linear stability analysis considering perturbation of the whole step train shows that the vicinal
is always unstable when the condition CL /CR >1 is fulfilled. Numerical integration of the equations of step motion combined with an original monitoring scheme(s) results
in obtaining the exact size- and time- scaling of the step bunches in the limit of long times (including the numerical prefactors).
Over a broad range of parameters the surface morphology is characterized by the appearance of the minimal interstep
distance at the beginning of the bunches (at the trailing edge of the bunch) and may be described by a single universality
class, different from those already generated by continuum theories [A. Pimpinelli et al., Phys. Rev. Lett. 88, 206103 (2002), J. Krug et al., Phys. Rev. B 71, 045412 (2005)]. In particular, the scaling of the minimal interstep distance lmin in the new universality class is shown to be lmin = (Sn /N)1/(n+1), where N is the number of steps in the bunch, n is the exponent in the step-step repulsion law U ~ 1/d0
n for two steps placed a distance d0 apart and Sn is a combination of the model parameters. It is also shown that N scales with time with universal exponent 1/2 independent
of n. For the regime of slow diffusion it is obtained for the first time that the time scaling depends only on the destabilization
parameter CL/CR. The bunching outside the parameter region where the above scaling exists cannot be assigned to a specific universality class
and thus should be considered non-universal. 相似文献
16.
R. T. Sibatov 《JETP Letters》2011,93(9):503-507
Distributions of the conductance G of a long quantum wire with the fractal distribution of barriers have been obtained in the successive incoherent tunneling
regime. The asymptotic behavior (in the limit L → ∞) of moments 〈G
k
(L)〉, average power of the shot noise 〈S(L)〉, and Fano factor agree with the results of the work [C. W. J. Beenakker et al., Phys. Rev. B 79, 024204 (2009)], and the distributions themselves describe well the Monte Carlo simulation results. The equation that has
been obtained for the distributions of the resistance and conductance agrees with the recent fractional differential generalization
of the Dorokhov-Mello-Pereyra-Kumar equation for the quasi-one-dimensional multichannel disordered semiconductors with a self-similar
distribution of scatterers. 相似文献
17.
Within the framework of the two-fluid hydrodynamics of plasmas it is shown that the problem instability of a thin current-carrying
layer admits two limiting cases which allow analytic solutions and complement one another. These limits are analogous to the
well-known shallow-water and deep-water approximations in the fluid mechanical “wave-breaking” instability. In this case,
the long-wave limit coincides with the “quasi-Chaplygin” dynamic system of Bulanov and Sasorov, Fiz Plazmy 4, 746 (1978) [Sov. J. Plasma Phys. 4, 418 (1978)], while the short-wavelength limit corresponds to the phenomenological model of Trubnikov, Usp. Fiz. Nauk 160, 167 (1990) [Sov. Phys. Usp. 33, 87 (1990)], for the clumping of “elementary” currents. In the latter case, strong collapse is unavoidable with the appearance
of current filaments that trap a finite current.
Zh. éksp. Teor. Fiz. 113, 1313–1318 (April 1998) 相似文献
18.
19.
W. Ekardt W.-D. Schöne R. Keyling 《Applied Physics A: Materials Science & Processing》2000,71(5):529-535
Experience has shown that theoretically determined lifetimes of bulk states of hot electrons in real metals agree quantitatively
with the experimental ones, if theory fully takes into account the crystal structure and many-body effects of the investigated
metal, i.e., if the Dyson equation is solved at the ab initio level and the effective electron–electron interaction is determined beyond the plasmon-pole approximation. Therefore the
hitherto invoked transport effect [Knoesel et al.: Phys. Rev. B 57, 12812 (1998)] does not seem to exist. In this paper we show that likewise neither virtual states [Hertel: et al. Phys. Rev.
Lett. 76, 535 (1996)] nor damped band-gap states [Ogawa: et al.: Phys. Rev. B 55, 10869 (1997)] exist, but that the hitherto unexplained d-band catastrophe in Cu [Cu(111), Cu(110)] can be naturally resolved
by the concept of the transient exciton. This is a new quasiparticle in metals, which owes its existence to the dynamical character of dielectric screening at the microscopic level. This means that excitons, though they do not exist under stationary
conditions, can be observed under ultrafast experimental conditions.
Received: 30 March 2000 / Accepted: 2 September 2000 / Published online: 12 October 2000 相似文献
20.
H. Shu S.-Z. Fu X.-G. Huang M.-X. Ma J. Wu J.-J. Ye J.-H. He Y. Gu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,44(2):367-370
Using the ninth laser beam (converted to 2ω) of
“Shenguang-II” laser facility and the beam smoothing technology of
lens-array [Appl. Opt. 25, 377 (1986); Phys. Plasmas. 9, 3201 (1995)],
a shock wave with 700 μm (the root-mean-square of
shock breakout time (RMS) RMS ≈ 6.32 ps) flat top was created. An Al-Al
four-step target was designed to do research on shock wave stability in an
Al target. And the shock stability experiment with the Al-Al four-step
target indicated that the shock wave steadily propagated in the Al target of
thickness of about 20–45 μm under the power density of ~ 1.0×1014 W/cm2. 相似文献