11-05-2011, 04:52 PM
Abstract
Traditional quantum key distribution schemes arecarried out one-on-one. Both quantum and classical channels areneeded between any two users. This paper presents a quantumcryptographic network based on entanglement swapping and akey manage center. People can fulfill key distribution betweenany two users. Only channels between manage center and usersare needed while users need no communications between eachother. So it can save resource effectively and it is more reliableand flexible
Keywords-quantum cryptography; quantumcryptographic network; quantum key distribution;entanglement swapping; Bell measurement.t
I. INTRODUCTION
Quantum information science is the integration of quantummechanics with information science. One of the most importantfields in quantum information science is quantum cryptography.Unlike classical cryptography schemes based on thecomputation complexity, in quantum cryptography thesecurities of cryptograph schemes are guaranteed by thefundamental principle of quantum mechanics. So quantumcryptographic schemes can be unconditionally secure. Asknown how to distribute a key is the most important and mostdifficult problem in classical cryptography. In fact there aren'tunconditionally secure key distribution schemes through aninsecure channel existing at all. Quantum keydistribution(QKD) scheme is a good way to solve this problem.In QKD schemes we can achieve unconditional keydistribution by use of an insecure quantum channel and aninsecure but unjammed classical channel. The first quantumkey distribution scheme is proposed by C. H. Bennett and G.Brassard in 1984 ( so called BB84 scheme) [1]. Since thenmany quantum key distribution schemes have been establishedand their securities have been studied, such as the EPRschemes [2], B92 [3], the scheme of Lo-Chau [4], and so on [5-18]. On the other hand experimental work for OKD has alsosucceeded. In 1992 Bennett