Repeatable classical one-time-pad crypto-system with quantum mechanics

Classical one-time-pad key can only be used once. We show in this Letter that with quantum mechanical information media classical one-time-pad key can be repeatedly used. We propose a specific realization using single photons. The reason why quantum mechanics can make the classical one-time-pad key repeatable is that quantum states can not be cloned and eavesdropping can be detected by the legitimate users. This represents a significant difference between classical cryptography and quantum cryptography and provides a new tool in designing quantum communication protocols and flexibility in practical applications. Note added: This work was submitted to PRL as LU9745 on 29 July 2004, and the decision was returned on 11 November 2004, which advised us to resubmit to some specialized journal, probably, PRA, after revision. We publish it here in memory of Prof. Fu-Guo Deng (1975.11.12-2019.1.18), from Beijing Normal University, who died on Jan 18, 2019 after two years heroic fight with pancreatic cancer. In this work, we designed a protocol to repeatedly use a classical one-time-pad key to transmit ciphertext using single photon states. The essential idea was proposed in November 1982, by Charles H. Bennett, Gilles Brassard, Seth Breidbart, which was rejected by Fifteenth Annual ACM Symposium on Theory of Computing, and remained unpublished until 2014, when they published the article, Quantum Cryptography II: How to re-use a one-time pad safely even if P=NP, Natural Computing (2014) 13:453-458, DOI 10.1007/s11047-014-9453-6. We worked out this idea independently. This work has not been published, and was in cooperated into quant-ph 706.3791 (Kai Wen, Fu Guo Deng, Gui Lu Long, Secure Reusable Base-String in Quantum Key Distribution), and quant-ph 0711.1642 (Kai Wen, Fu-Guo Deng, Gui Lu Long, Reusable Vernam Cipher with Quantum Media).Comment: It was submitted to PRL in 2004. We designed a protocol to use repeatedly a one-time-pad to transmit ciphertext using single photons. The idea was proposed by Bennett, Brassard, Breidbart in 1982. Unknowing their work, we rediscovered this idea independently. We publish it here in memory of Prof. Fu-Guo Deng (1975.11.12-2019.1.18), who died after two years heroic fight with pancreatic cance

Complete hyperentangled-Bell-state analysis for quantum communication

It is impossible to unambiguously distinguish the four Bell states in polarization, resorting to linear optical elements only. Recently, the hyperentangled Bell state, the simultaneous entanglement in more than one degree of freedom, has been used to assist in the complete Bell-state analysis of the four Bell states. However, if the additional degree of freedom is qubitlike, one can only distinguish 7 from the group of 16 states. Here we present a way to distinguish the hyperentangled Bell states completely with the help of cross-Kerr nonlinearity. Also, we discuss its application in the quantum teleportation of a particle in an unknown state in two different degrees of freedom and in the entanglement swapping of hyperentangled states. These applications will increase the channel capacity of long-distance quantum communication.Comment: 9 pages, 6 figure

Water Injection in Longwall Top-coal Caving Face in China

This paper discussed the means of improving dust control efficiency using water injection. At first, the authors point out that internal water has effect on dust control. The objective of water injection is to increase the amount of internal water. Secondly, by analyzing the development trend of crack in top-coal, proper water injection station and boleholes can be determined for dust control

Establishing language skills in Europe: The Inspirations on Chinese Foreign Language Study

In order to promote transparency and coherence for language learning, teaching and especially estimate, Council of Europe(CoE）developed the Common European Framework of Reference(CEFR) and European Language Portfolio(ELP).The CEFR and the ELP are one of the most influential documents of the last decade in the fields of language learning and teaching in Europe and elsewhere. It is therefore also very important for the contacts between Europe and China, in educational contact as well as in professional contexts. Key words: Europe; language Skill; The Common European Framework of Reference; European Language PortfolioRésumé: Afin de promouvoir la transparence et la cohérence pour l'apprentissage, l’enseignement et l’évaluation des langues, le Conseil de l'Europe (CoE) a élaboré le Cadre européen commun de référence (CECR) et le Portfolio européen des langues (PEL). Le CECR et le PEL sont l'un des documents les plus influents de la dernière décennie dans les domaines de l'apprentissage et de l'enseignement des langues en Europe et ailleurs. Il est donc ainsi très important pour les contacts entre l'Europe et la Chine, non seulement dans le contexte pédagogique, mais aussi dans des contextes professionnels.Mots-clés : Europe; compétences linguistiques; Cadre européen commun de référence; Portfolio européen des langue

LL-fuzzy ideal degrees in effect algebras

summary:In this paper, considering $L$ being a completely distributive lattice, we first introduce the concept of $L$-fuzzy ideal degrees in an effect algebra $E$, in symbol $\mathfrak{D}_{ei}$. Further, we characterize $L$-fuzzy ideal degrees by cut sets. Then it is shown that an $L$-fuzzy subset $A$ in $E$ is an $L$-fuzzy ideal if and only if $\mathfrak{D}_{ei}(A)=\top,$ which can be seen as a generalization of fuzzy ideals. Later, we discuss the relations between $L$-fuzzy ideals and cut sets ($L_{\beta}$-nested sets and $L_{\alpha}$-nested sets). Finally, we obtain that the $L$-fuzzy ideal degree is an $(L,L)$-fuzzy convexity. The morphism between two effect algebras is an $(L,L)$-fuzzy convexity-preserving mapping