With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modifi...With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modification of the original concept of set covering problem. It is also different from the concept of exact cover defined by J.E. Hopcmft. Some properties of （k, n ） -exact cover are investigated; a sufficient condition for a set to be （ k, n ） -exactly coverable is given. It follows that a feasible assignment scheme of a set for the （ k, n） -exact eover is obtained if this set satisfies the sufficient condition.展开更多
A two-step deterministic secure quantum communication （DSQC） scheme using blocks of three-qubit W state is proposed. In this scheme, the secret messages can be encoded by employing four two-particle unitary operatio...A two-step deterministic secure quantum communication （DSQC） scheme using blocks of three-qubit W state is proposed. In this scheme, the secret messages can be encoded by employing four two-particle unitary operations and directly decoded by utilizing the corresponding measurements in Bell basis or single-particle basis. Comparing with most previous DSQC protocols, the present scheme has a high total efficiency, which comes up to 50%. Apart from this, it has still the advantages of high capacity as each W state can carry two bits of secret information, and high intrinsic efficiency because almost all the instances are useful. Furthermore, the security of this communication can be ensured by the decoy particle checking technique and the two-step transmitting idea.展开更多
基金Supported by the National Natural Science Foundation of China (No. 60673053 90718011 )
文摘With the （ k, n ）-threshold scheme of secret sharing in the field of information security technology as an application background, the concept of set （ k, n ）-exact cover is presented in this paper. It is a modification of the original concept of set covering problem. It is also different from the concept of exact cover defined by J.E. Hopcmft. Some properties of （k, n ） -exact cover are investigated; a sufficient condition for a set to be （ k, n ） -exactly coverable is given. It follows that a feasible assignment scheme of a set for the （ k, n） -exact eover is obtained if this set satisfies the sufficient condition.
基金Supported by the Key Project of the Education Department of Anhui Province under Grant No.KJ2010A323the Talent Project of the Anhui Province for Outstanding Youth under Grant Nos.2009SQRZ190,2010SQRL186,2010SQRL187 and 2011SQRL147the Natural Science Research Programme of the Education Department of Anhui Province under Grant No.KJ2009B018Z
文摘A two-step deterministic secure quantum communication （DSQC） scheme using blocks of three-qubit W state is proposed. In this scheme, the secret messages can be encoded by employing four two-particle unitary operations and directly decoded by utilizing the corresponding measurements in Bell basis or single-particle basis. Comparing with most previous DSQC protocols, the present scheme has a high total efficiency, which comes up to 50%. Apart from this, it has still the advantages of high capacity as each W state can carry two bits of secret information, and high intrinsic efficiency because almost all the instances are useful. Furthermore, the security of this communication can be ensured by the decoy particle checking technique and the two-step transmitting idea.
