28,772 research outputs found
Practical Certificateless Aggregate Signatures From Bilinear Maps
Aggregate signature is a digital signature with a striking property that anyone can aggregate n individual signatures on n different messages which are signed by n distinct signers, into a single compact signature to reduce computational and storage costs. In this work, two practical certificateless aggregate signature schemes are proposed from bilinear maps. The first scheme CAS-1 reduces the costs of communication and signer-side computation but trades off the storage, while CAS-2 minimizes the storage but sacrifices the communication costs. One can choose either of the schemes by consideration of the application requirement. Compare with ID-based schemes, our schemes do not entail public key certificates as well and achieve the trust level 3, which imply the frauds of the authority are detectable. Both of the schemes are proven secure in the random oracle model by assuming the intractability of the computational Diffie-Hellman problem over the groups with bilinear maps, where the forking lemma technique is avoided
Observation of valley Landau-Zener-Bloch oscillations and pseudospin imbalance in photonic graphene
We demonstrate inter-valley Bloch oscillation (BO) and Landau-Zener tunneling
(LZT) in an optically-induced honeycomb lattice with a refractive index
gradient. Unlike previously observed BO in a gapped square lattice, we show
non-adiabatic beam dynamics that are highly sensitive to the direction of the
index gradient and the choice of the Dirac cones. In particular, a
symmetry-preserving potential leads to nearly perfect LZT and coherent BO
between the inequivalent valleys, whereas a symmetry-breaking potential
generates asymmetric scattering, imperfect LZT, and valley-sensitive generation
of vortices mediated by a pseudospin imbalance. This clearly indicates that,
near the Dirac points, the transverse gradient does not always act as a simple
scalar force as commonly assumed, and the LZT probability is strongly affected
by the sublattice symmetry as analyzed from an effective Landau-Zener
Hamiltonian. Our results illustrate the anisotropic response of an otherwise
isotropic Dirac platform to real-space potentials acting as strong driving
fields, which may be useful for manipulation of pseudospin and valley degrees
of freedom in graphene-like systems
Plaquette valence bond state in spin-1/2 J1-J2 XY model on square lattice
We studied the ground state phase diagram of spin-1/2 J1-J2 XY model on the
square lattice with first- J1 and second-neighbor J2 antiferromagnetic
interactions using both iDMRG and DMRG approaches. We show that a plaquette
valence bond phase is realized in an intermediate region 0.50 <= J2/J1 <= 0.54
between a N\'eel magnetic ordered phase at J2/J1 < 0.50 and a stripy magnetic
ordered phase at J2/J1 >= 0.54. The plaquette valence bond phase is
characterized by finite dimer orders in both the horizontal and vertical
directions. Contrary to the spin-1/2 J1-J2 Heisenberg model, we do not find
numerical evidence for a quantum spin liquid phase in the J1-J2 XY model.Comment: 7 pages, 5 figure
A Note on the Generalization of the GEMS Approach
This paper is a supplement of our earlier work JHEP 0410 (2004)
011[gr-qc/0409107].We map the vector potential of charged black holes into GEMS
and find that its effect on the thermal spectrum is the same as that on the
black hole side, i.e., it will induce a chemical potential in the thermal
spectrum which is the same as that in the charged black holes.We also argue
that the generalization of GEMS approach to non-stationary motions is not
possible.Comment: Latex file, 10 pages, no figure; v2: minor corrections; v3: revised
with title changed, one new section added and references adde
Effects of organic nitrogen and carbon sources on mycelial growth and polysaccharides production and their optimization in the submerged culture of Grifola umbellate, a Chinese medicinal herb
Grifola umbellate is a famous and expensive Chinese herb medicine and the main medicinal component is polysaccharide mainly produced by its mycelia. Effects of organic nitrogen and carbon resources on mycelial growth and polysaccharides production of a medicinal mushroom, G. umbellate were studied in the submerged culture system. Soybean meal was selected as the optimal organic nitrogen source for its significant promotion effects on mycelial growth and polysaccharides synthesis based on results of an orthogonal matrix experiment design. Glucose was proved to be a preferred carbon source by comparison with fructose and sucrose. The optimal dosages of soybean meal 5.63% (w/v) and glucose 4.33% (w/v) were obtained, respectively through the curvilinear regressions experiment. The productions of mycelial dry weight, exo-polysaccharide (EPS) and inner polysaccharide (IPS), in the optimal medium, were about 3.16, 1.48 and 2.78 folds higher than those in the basal medium, respectively and culture duration was shortened to half through optimizing the organic nitrogen and carbon sources. These results will be significant contribution to process biochemistry of medicinal fungus in the submerged culture system
Effects of losses in the hybrid atom-light interferometer
Enhanced Raman scattering can be obtained by injecting a seeded light field
which is correlated with the initially prepared collective atomic excitation.
This Raman amplification process can be used to realize atom-light hybrid
interferometer. We numerically calculate the phase sensitivities and the
signal-to-noise ratios of this interferometer with the method of homodyne
detection and intensity detection, and give their differences between this two
methods. In the presence of loss of light field and atomic decoherence the
measure precision will be reduced which can be explained by the break of the
intermode decorrelation conditions of output modesComment: 9 pages, 7 figure
Effects of Mirror Aberrations on Laguerre-Gaussian Beams in Interferometric Gravitational-Wave Detectors
A fundamental limit to the sensitivity of optical interferometers is imposed
by Brownian thermal fluctuations of the mirrors' surfaces. This thermal noise
can be reduced by using larger beams which "average out" the random
fluctuations of the surfaces. It has been proposed previously that wider,
higher-order Laguerre-Gaussian modes can be used to exploit this effect. In
this article, we show that susceptibility to spatial imperfections of the
mirrors' surfaces limits the effectiveness of this approach in interferometers
used for gravitational-wave detection. Possible methods of reducing this
susceptibility are also discussed.Comment: 10 pages, 11 figure
- …