31,519 research outputs found
Cryptanalysis of the Hillery-Buzek-Berthiaume quantum secret-sharing protocol
The participant attack is the most serious threat for quantum secret-sharing
protocols. We present a method to analyze the security of quantum
secret-sharing protocols against this kind of attack taking the scheme of
Hillery, Buzek, and Berthiaume (HBB) [Phys. Rev. A 59 1829 (1999)] as an
example. By distinguishing between two mixed states, we derive the necessary
and sufficient conditions under which a dishonest participant can attain all
the information without introducing any error, which shows that the HBB
protocol is insecure against dishonest participants. It is easy to verify that
the attack scheme of Karlsson, Koashi, and Imoto [Phys. Rev. A 59, 162 (1999)]
is a special example of our results. To demonstrate our results further, we
construct an explicit attack scheme according to the necessary and sufficient
conditions. Our work completes the security analysis of the HBB protocol, and
the method presented may be useful for the analysis of other similar protocols.Comment: Revtex, 7 pages, 3 figures; Introduction modifie
Eļ¬ects of micro-molar H2O2 on inhibiting soil nitriļ¬cation
Microcosm experiments were conducted to examine the eļ¬ects of micro-molar hydrogen peroxide (H2O2) on soil nitriļ¬cation in three scenarios: (a) without added fresh biomass and magnetite, (b) with added fresh biomass, and (c) with added magnetite. The results show that nitriļ¬cation of the added ammonium was impeded in the presence of H2O2 at a concentration range of 20ā50Ī¼M probably as a result of weakened activities of ammoniaoxidizing microbes due to oxidative stress caused by H2O2 and possibly hydroxyl radical (Ā·OH). Application of grass clippings or magnetite enhanced the eļ¬ects of H2O2 on inhibiting soil nitriļ¬cation. The research ļ¬ndings obtained from this study have implications for understanding the complication of soil nitriļ¬cation by rainwaterborne H2O2 during ļ¬ood events and developing cost-eļ¬ective and environmentally friendly techniques for nitriļ¬cation inhibition in fertilized soils
Singular electrostatic energy of nanoparticle clusters
The binding of clusters of metal nanoparticles is partly electrostatic. We
address difficulties in calculating the electrostatic energy when high charging
energies limit the total charge to a single quantum, entailing unequal
potentials on the particles. We show that the energy at small separation
has a strong logarithmic dependence on . We give a general law for the
strength of this logarithmic correction in terms of a) the energy at contact
ignoring the charge quantization effects and b) an adjacency matrix specifying
which spheres of the cluster are in contact and which is charged. We verify the
theory by comparing the predicted energies for a tetrahedral cluster with an
explicit numerical calculation.Comment: 17 pages, 3 figures. Submitted to Phys Rev
Radiative and Collisional Jet Energy Loss in a Quark-Gluon Plasma
We calculate radiative and collisional energy loss of hard partons traversing
the quark-gluon plasma created at RHIC and compare the respective size of these
contributions. We employ the AMY formalism for radiative energy loss and
include additionally energy loss by elastic collisions. Our treatment of both
processes is complete at leading order in the coupling, and accounts for the
probabilistic nature of jet energy loss. We find that a solution of the
Fokker-Planck equation for the probability density distributions of partons is
necessary for a complete calculation of the nuclear modification factor
for pion production in heavy ion collisions. It is found that the
magnitude of is sensitive to the inclusion of both collisional and
radiative energy loss, while the average energy is less affected by the
addition of collisional contributions. We present a calculation of for
at RHIC, combining our energy loss formalism with a relativistic
(3+1)-dimensional hydrodynamic description of the thermalized medium.Comment: 4 pages, 4 figures, contributed to Quark Matter 2008, Jaipur, Indi
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