In recent years,Blockchain is gaining prominence as a hot topic in academic research.However,the consensus mechanism of blockchain has been criticized in terms of energy consumption and performance.Although Proof-of-A...In recent years,Blockchain is gaining prominence as a hot topic in academic research.However,the consensus mechanism of blockchain has been criticized in terms of energy consumption and performance.Although Proof-of-Authority(PoA)consensus mechanism,as a lightweight consensus mechanism,is more efficient than traditional Proof-of-Work(PoW)and Proof-of-Stake(PoS),it suffers from the problem of centralization.To this end,on account of analyzing the shortcomings of existing consensus mechanisms,this paper proposes a dynamic reputation-based consensus mechanism for blockchain.This scheme allows nodes with reputation value higher than a threshold apply to become a monitoring node,which can monitor the behavior of validators in case that validators with excessive power cause harm to the blockchain network.At the same time,the reputation evaluation algorithm is also introduced to select nodes with high reputation to become validators in the network,thus increasing the cost of malicious behavior.In each consensus cycle,validators and monitoring nodes are dynamically updated according to the reputation value.Through security analysis,it is demonstrated that the scheme can resist the attacks of malicious nodes in the blockchain network.By simulation experiments and analysis of the scheme,the result verifies that the mechanism can effectively improve the fault tolerance of the consensus mechanism,reduce the time of consensus to guarantee the security of the system.展开更多
In this study, we investigate the phenomenon of distillability sudden death （DSD） for a two-qutrit system coupled to an XY spin chain. In virtue of the negativity and realignment criterion, we show that certain init...In this study, we investigate the phenomenon of distillability sudden death （DSD） for a two-qutrit system coupled to an XY spin chain. In virtue of the negativity and realignment criterion, we show that certain initial-prepared free entangled states may become bound entangled states in a finite time. The possibility of a DSD not only depends on the initial state parameter, but is also determined by the coupling between the two-qutrit system and the spin chain. The effects of other parameters related with the system and the spin chain （e.g., the total number of spins in the spin chain, strengths of the transverse field, and anisotropy parameter） on the time-determined bound entangled state are also investigated in detail. Accordingly, some effective methods of controlling the DSD are proposed.展开更多
基金This work is supported by the Key Research and Development Project of Sichuan Province(No.2021YFSY0012,No.2020YFG0307,No.2021YFG0332)the Key Research and Development Project of Chengdu(No.2019-YF05-02028-GX)+1 种基金the Innovation Team of Quantum Security Communication of Sichuan Province(No.17TD0009)the Academic and Technical Leaders Training Funding Support Projects of Sichuan Province(No.2016120080102643).
文摘In recent years,Blockchain is gaining prominence as a hot topic in academic research.However,the consensus mechanism of blockchain has been criticized in terms of energy consumption and performance.Although Proof-of-Authority(PoA)consensus mechanism,as a lightweight consensus mechanism,is more efficient than traditional Proof-of-Work(PoW)and Proof-of-Stake(PoS),it suffers from the problem of centralization.To this end,on account of analyzing the shortcomings of existing consensus mechanisms,this paper proposes a dynamic reputation-based consensus mechanism for blockchain.This scheme allows nodes with reputation value higher than a threshold apply to become a monitoring node,which can monitor the behavior of validators in case that validators with excessive power cause harm to the blockchain network.At the same time,the reputation evaluation algorithm is also introduced to select nodes with high reputation to become validators in the network,thus increasing the cost of malicious behavior.In each consensus cycle,validators and monitoring nodes are dynamically updated according to the reputation value.Through security analysis,it is demonstrated that the scheme can resist the attacks of malicious nodes in the blockchain network.By simulation experiments and analysis of the scheme,the result verifies that the mechanism can effectively improve the fault tolerance of the consensus mechanism,reduce the time of consensus to guarantee the security of the system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11305114, 11304226, and 11505126)
文摘In this study, we investigate the phenomenon of distillability sudden death （DSD） for a two-qutrit system coupled to an XY spin chain. In virtue of the negativity and realignment criterion, we show that certain initial-prepared free entangled states may become bound entangled states in a finite time. The possibility of a DSD not only depends on the initial state parameter, but is also determined by the coupling between the two-qutrit system and the spin chain. The effects of other parameters related with the system and the spin chain （e.g., the total number of spins in the spin chain, strengths of the transverse field, and anisotropy parameter） on the time-determined bound entangled state are also investigated in detail. Accordingly, some effective methods of controlling the DSD are proposed.
