We present an efficient scheme for sharing an arbitrary m-qubit state with n agents.In our scheme,the sender Alice first shares m Bell states with the agent Bob,who is designated to recover the original m-qubit state....We present an efficient scheme for sharing an arbitrary m-qubit state with n agents.In our scheme,the sender Alice first shares m Bell states with the agent Bob,who is designated to recover the original m-qubit state.Furthermore,Alice introduces n-1 auxiliary particles in the initial state |0>,applies Hadamard (H) gate and Controlled-Not(CNOT) gate operations on the particles,which make them entangled with one of m particle pairs in Bell states,and then sends them to the controllers (i.e.,other n-1 agents),where each controller only holds one particle in hand.After Alice performing m Bell-basis measurements and each controller a single-particle measurement,the recover Bobcan obtain the original unknown quantum state by applying the corresponding local unitary operations on his particles.Its intrinsic efficiency for qubits approaches 100%,and the total efficiency really approaches the maximal value.展开更多
Twenty-one typical coupled large samples were chosen from areas within and surrounding nature reserves on the Tibetan Plateau using the large sample comparison method(LSCM).To evaluate the effectiveness of the nature ...Twenty-one typical coupled large samples were chosen from areas within and surrounding nature reserves on the Tibetan Plateau using the large sample comparison method(LSCM).To evaluate the effectiveness of the nature reserves in protecting the ecological environment,the alpine grassland net primary production(NPP) of these coupled samples were compared and the differences between them before and after their establishment as protected areas were analyzed.The results showed that:(1) With respect to the alpine grassland NPP,the ecological and environmental conditions of most nature reserves were more fragile than those of the surrounding areas and also lower than the average values for the Tibetan Plateau.(2) Of the 11 typical nature reserves selected,the positive trend in the NPP for Manzetang was the most significant,whereas there was no obvious trend in Taxkorgan.With the exception of Selincuo,the annual NPP growth rate in the nature reserves covered by alpine meadow and wetland was higher than that in nature reserves consisting of alpine steppe and alpine desert.(3) There were notable findings in 21 typical coupled samples:(a) After the establishment of the nature reserves,the annual rate of increase in the NPP in 76% of samples inside nature reserves and 82% of samples inside national nature reserves was higher than that of the corresponding samples outside nature reserves.(b) The effectiveness of ecological protection of the Mid-Kunlun,Changshagongma,Zoige and Selincuo(Selin Co) nature reserves was significant; the effectiveness of protection was relatively sig-nificant in most parts of the Sanjiangyuan and Qiangtang nature reserves,whereas in south-east Manzetang and north Taxkorgan the protection effectiveness was not obvious.(c) The ecological protection effectiveness was significant in nature reserves consisting of alpine meadow,but was weak in nature reserves covered by alpine steppe.This study also shows that the advantage of large sample comparison method in evaluating regional ecology change.Careful design of the samples used,to ensure comparability between the samples,is crucial to the success of this LSCM.展开更多
基金Supported by the Major Research Plan of the National Natural Science Foundation of China under Grant No.90818005the National Natural Science Foundation of China under Grant Nos.60903217,60773032 60773114the Ph.D.Program Foundation of Ministry of Education of China under Grant No.20060358014
文摘We present an efficient scheme for sharing an arbitrary m-qubit state with n agents.In our scheme,the sender Alice first shares m Bell states with the agent Bob,who is designated to recover the original m-qubit state.Furthermore,Alice introduces n-1 auxiliary particles in the initial state |0>,applies Hadamard (H) gate and Controlled-Not(CNOT) gate operations on the particles,which make them entangled with one of m particle pairs in Bell states,and then sends them to the controllers (i.e.,other n-1 agents),where each controller only holds one particle in hand.After Alice performing m Bell-basis measurements and each controller a single-particle measurement,the recover Bobcan obtain the original unknown quantum state by applying the corresponding local unitary operations on his particles.Its intrinsic efficiency for qubits approaches 100%,and the total efficiency really approaches the maximal value.
基金The Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDB03030500National Key Technology Research and Development Program,No.2013BAC04B02+1 种基金Key Foundation Project of Basic Work of the Ministry of Science and Technology of China,No.2012FY111400National Natural Science Foundation of China,No.41171080,No.41201095
文摘Twenty-one typical coupled large samples were chosen from areas within and surrounding nature reserves on the Tibetan Plateau using the large sample comparison method(LSCM).To evaluate the effectiveness of the nature reserves in protecting the ecological environment,the alpine grassland net primary production(NPP) of these coupled samples were compared and the differences between them before and after their establishment as protected areas were analyzed.The results showed that:(1) With respect to the alpine grassland NPP,the ecological and environmental conditions of most nature reserves were more fragile than those of the surrounding areas and also lower than the average values for the Tibetan Plateau.(2) Of the 11 typical nature reserves selected,the positive trend in the NPP for Manzetang was the most significant,whereas there was no obvious trend in Taxkorgan.With the exception of Selincuo,the annual NPP growth rate in the nature reserves covered by alpine meadow and wetland was higher than that in nature reserves consisting of alpine steppe and alpine desert.(3) There were notable findings in 21 typical coupled samples:(a) After the establishment of the nature reserves,the annual rate of increase in the NPP in 76% of samples inside nature reserves and 82% of samples inside national nature reserves was higher than that of the corresponding samples outside nature reserves.(b) The effectiveness of ecological protection of the Mid-Kunlun,Changshagongma,Zoige and Selincuo(Selin Co) nature reserves was significant; the effectiveness of protection was relatively sig-nificant in most parts of the Sanjiangyuan and Qiangtang nature reserves,whereas in south-east Manzetang and north Taxkorgan the protection effectiveness was not obvious.(c) The ecological protection effectiveness was significant in nature reserves consisting of alpine meadow,but was weak in nature reserves covered by alpine steppe.This study also shows that the advantage of large sample comparison method in evaluating regional ecology change.Careful design of the samples used,to ensure comparability between the samples,is crucial to the success of this LSCM.
