1,354 research outputs found
catena-Poly[[[dichloridozinc(II)]-μ-1,4-bis(1H-benzimidazol-2-yl-κN 3)butane] 1,4-bis(1H-benzimidazol-2-yl)butane solvate]
In the crystal structure of the title coordination polymer/co-crystal, {[ZnCl2(C18H18N4)]·C18H18N4}n, the tetrahedrally coordinated ZnII ions are linked by the N-heterocycle into a linear chain. Another N-heterocycle present is not coordinated to the metal atom but interacts with the chain through N—H⋯N and N—H⋯Cl hydrogen bonds. The butyl chain of the uncoordinated ligand is disordered over three positions in a 0.511 (4):0.289 (5):0.200 (5) ratio
Advantages of Asynchronous Measurement-Device-Independent Quantum Key Distribution in Intercity Networks
The new variant of measurement-device-independent quantum key distribution
(MDI-QKD), called asynchronous MDI-QKD or mode-pairing MDI-QKD, offers similar
repeater-like rate-loss scaling but has the advantage of simple technology
implementation by exploiting an innovative post-measurement pairing technique.
We herein present an evaluation of the practical aspects of decoy-state
asynchronous MDI-QKD. To determine its effectiveness, we analyze the optimal
method of decoy-state calculation and examine the impact of asymmetrical
channels and multi-user networks. Our simulations show that, under realistic
conditions, aynchronous MDI-QKD can furnish the highest key rate with MDI
security as compared to other QKD protocols over distances ranging from 50 km
to 480 km. At fiber distances of 50 km and 100 km, the key rates attain 6.02
Mbps and 2.29 Mbps respectively, which are sufficient to facilitate real-time
one-time-pad video encryption. Our findings indicate that experimental
implementation of asynchronous MDI-QKD in intercity networks can be both
practical and efficient
Experimental quantum secure network with digital signatures and encryption
Cryptography promises four information security objectives, namely,
confidentiality, integrity, authenticity, and non-repudiation, to support
trillions of transactions annually in the digital economy. Efficient digital
signatures, ensuring the integrity, authenticity, and non-repudiation of data
with information-theoretical security are highly urgent and intractable open
problems in cryptography. Here, we propose a protocol of high-efficiency
quantum digital signatures using secret sharing, one-time universal
hashing, and the one-time pad. We just need to use a 384-bit key to sign
documents of up to lengths with a security bound of . If
one-megabit document is signed, the signature efficiency is improved by more
than times compared with previous quantum digital signature protocols.
Furthermore, we build the first all-in-one quantum secure network integrating
information-theoretically secure communication, digital signatures, secret
sharing, and conference key agreement and experimentally demonstrate this
signature efficiency advantage. Our work completes the cryptography toolbox of
the four information security objectives.Comment: 19 pages, 7 figures, 4 tables. Quantum digital signatures and quantum
private communication maintain a consistent level of practicalit
Sub-femtosecond electron bunches in laser wakefield acceleration via injection suppression with a magnetic field
It is shown that electron injection into a laser-driven plasma bubble can be manipulated by applying an external magnetic field in the presence of a plasma density gradient. The down-ramp of the density-tailored plasma locally reduces the plasma wave phase velocity, which triggers injection. The longitudinal magnetic field dynamically induces an expanding hole in the electron density distribution at the rear of the wake bubble, which reduces the peak electron velocity in its vicinity. Electron injection is suppressed when the electron velocity drops below the phase velocity, which depends on the size of the density hole. This enables the start and end of electron injection to be independently controlled, which allows generation of sub-femtosecond electron bunches with peak currents of a few kilo-Ampere, for an applied magnetic field of ∼ 10 Tesla
Mechanisms underlying Actinobacillus pleuropneumoniae exotoxin ApxI induced expression of IL-1β, IL-8 and TNF-α in porcine alveolar macrophages
Actinobacillus pleuropneumoniae (A. pleuropneumoniae) causes fibrino-hemorrhagic necrotizing pleuropneumonia in pigs. Production of proinflammatory mediators in the lungs is an important feature of A. pleuropneumoniae infection. However, bacterial components other than lipopolysaccharide involved in this process remain unidentified. The goals of this study were to determine the role of A. pleuropneumoniae exotoxin ApxI in cytokine induction and to delineate the underlying mechanisms. Using real-time quantitative PCR analysis, we found native ApxI stimulated porcine alveolar macrophages (PAMs) to transcribe mRNAs of IL-1β, IL-8 and TNF-α in a concentration- and time-dependent manner. Heat-inactivation or pre-incubation of ApxI with a neutralizing antiserum attenuated ApxI bioactivity to induce cytokine gene expression. The secretion of IL-1β, IL-8 and TNF-α protein from PAMs stimulated with ApxI was also confirmed by quantitative ELISA. In delineating the underlying signaling pathways contributing to cytokine expression, we observed mitogen-activated protein kinases (MAPKs) p38 and cJun NH2-terminal kinase (JNK) were activated upon ApxI stimulation. Administration of an inhibitor specific to p38 or JNK resulted in varying degrees of attenuation on ApxI-induced cytokine expression, suggesting the differential regulatory roles of p38 and JNK in IL-1β, IL-8 and TNF-α production. Further, pre-incubation of PAMs with a CD18-blocking antibody prior to ApxI stimulation significantly reduced the activation of p38 and JNK, and subsequent expression of IL-1β, IL-8 or TNF-α gene, indicating a pivotal role of β2 integrins in the ApxI-mediated effect. Collectively, this study demonstrated ApxI induces gene expression of IL-1β, IL-8 and TNF-α in PAMs that involves β2 integrins and downstream MAPKs
Simple security proof of coherent-one-way quantum key distribution
Coherent-one-way quantum key distribution (COW-QKD), which requires a simple
experimental setup and has the ability to withstand photon-number-splitting
attacks, has been not only experimentally implemented but also commercially
applied. However, recent studies have shown that the current COW-QKD system is
insecure and can only distribute secret keys safely within 20 km of the optical
fiber length. In this study, we propose a practical implementation of COW-QKD
by adding a two-pulse vacuum state as a new decoy sequence. This proposal
maintains the original experimental setup as well as the simplicity of its
implementation. Utilizing detailed observations on the monitoring line to
provide an analytical upper bound on the phase error rate, we provide a
high-performance COW-QKD asymptotically secure against coherent attacks. This
ensures the availability of COW-QKD within 100 km and establishes theoretical
foundations for further applications.Comment: 8 pages, 5 figures, 1 tabl
Beating the fault-tolerance bound and security loopholes for Byzantine agreement with a quantum solution
Byzantine agreement, the underlying core of blockchain, aims to make every
node in a decentralized network reach consensus. Classical Byzantine agreements
unavoidably face two major problems. One is fault-tolerance bound, which
means that the system to tolerate malicious players requires at least
players. The other is the security loopholes from its classical
cryptography methods. Here, we propose a strict quantum Byzantine agreement
with unconditional security to break this bound with nearly fault
tolerance due to multiparty correlation provided by quantum digital signatures.
Our work strictly obeys the original Byzantine conditions and can be extended
to any number of players without requirements for multiparticle entanglement.
We experimentally demonstrate three-party and five-party quantum consensus for
a digital ledger. Our work indicates the quantum advantage in terms of
consensus problems and suggests an important avenue for quantum blockchain and
quantum consensus networks.Comment: 22 pages, 10 figures. All comments are welcome
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