Measurement-device-independent quantum key distribution （MDI-QKD） can be immune to all detector side- channel attacks and guarantee the information-theoretical security even with uncharacterized single photon detect...Measurement-device-independent quantum key distribution （MDI-QKD） can be immune to all detector side- channel attacks and guarantee the information-theoretical security even with uncharacterized single photon detectors. MDI-QKD has been demonstrated in both laboratories and field-tests by using attenuated lasers combined with the decoy-state technique. However, it is a critical assumption that the sources used by legitimate participants are trusted in MDI-QKD. Hence, it is possible that a potential security risk exists. Here we propose a new scheme of polarization-encoding-based MDI-QKD with a single untrusted source, by which the complexity of the synchronization system can be reduced and the success rate of the Bell-state measurement can be improved. Meanwhile, the decoy-state method is employed to avoid the security issues introduced by a non-ideal single photon source. We also derive a security analysis of the proposed system. In addition, it seems to be a promising candidate for the implementation for QKD network in the near future.展开更多
Blue stragglers are a common observational fact for the Galactic clusters. Single Stellar Populations (SSPs) are basic to the studies of galaxy structre and evolution. SSPs are mainly based either on the observation o...Blue stragglers are a common observational fact for the Galactic clusters. Single Stellar Populations (SSPs) are basic to the studies of galaxy structre and evolution. SSPs are mainly based either on the observation of the integrated properties of star clusters, or on the theoretical understandings of single star evolution. Both of the two ways of making SSPs suffer from either observational uncertainties concerning field contaminations or lack of good models for close binary systems. Based on the photometry of the classical open cluster M67 and the thorough membership survey, we made a color-magnitude diagram (CMD) of high membership stars for the cluster. We will show that by including the contributions of the bright blue stragglers that is common to open clusters, the integrated properties of the clusters are quite different from tranditional SSP models. We further conclude that these blue light contributors are very important to SSP models, and may cast new lights on its applications in the studies of galaxies.展开更多
A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation dur...A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation during solidification was researched.In the present work,these analytical methods were further extended.Combined with an original vectorization method,a 3D Rosenthal solution was used to determine thermal conditions of the welds.Afterward,the dendrite growth orientation,the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted.Finally,the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot.The results indicate that substrate orientation has some impacts on the crystal growth pattern,dendrite growth velocity,distribution of thermal gradient and stray grain.Based on the research methods proposed in this work,any substrate crystallographic orientation can be studied,and predicted stray grains distribution can be visualized.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 61372076 and 61301171the 111 Project under Grant No B08038
文摘Measurement-device-independent quantum key distribution （MDI-QKD） can be immune to all detector side- channel attacks and guarantee the information-theoretical security even with uncharacterized single photon detectors. MDI-QKD has been demonstrated in both laboratories and field-tests by using attenuated lasers combined with the decoy-state technique. However, it is a critical assumption that the sources used by legitimate participants are trusted in MDI-QKD. Hence, it is possible that a potential security risk exists. Here we propose a new scheme of polarization-encoding-based MDI-QKD with a single untrusted source, by which the complexity of the synchronization system can be reduced and the success rate of the Bell-state measurement can be improved. Meanwhile, the decoy-state method is employed to avoid the security issues introduced by a non-ideal single photon source. We also derive a security analysis of the proposed system. In addition, it seems to be a promising candidate for the implementation for QKD network in the near future.
文摘Blue stragglers are a common observational fact for the Galactic clusters. Single Stellar Populations (SSPs) are basic to the studies of galaxy structre and evolution. SSPs are mainly based either on the observation of the integrated properties of star clusters, or on the theoretical understandings of single star evolution. Both of the two ways of making SSPs suffer from either observational uncertainties concerning field contaminations or lack of good models for close binary systems. Based on the photometry of the classical open cluster M67 and the thorough membership survey, we made a color-magnitude diagram (CMD) of high membership stars for the cluster. We will show that by including the contributions of the bright blue stragglers that is common to open clusters, the integrated properties of the clusters are quite different from tranditional SSP models. We further conclude that these blue light contributors are very important to SSP models, and may cast new lights on its applications in the studies of galaxies.
基金financially supported by the National Natural Science Foundation of China(Nos.51401210 and51271186)the National High Technology Research and Development Program of China(No.2014AA041701)
文摘A geometric analysis technique for crystal growth and microstructure development in single-crystal welds had been previously developed.And the effect of welding conditions on the tendency of stray grains formation during solidification was researched.In the present work,these analytical methods were further extended.Combined with an original vectorization method,a 3D Rosenthal solution was used to determine thermal conditions of the welds.Afterward,the dendrite growth orientation,the dendrite growth velocity and the thermal gradient along dendrite direction were calculated and lively plotted.Finally,the tendency of stray grains formation in the solidification front was forecasted and its distribution was presented with a 3D plot.The results indicate that substrate orientation has some impacts on the crystal growth pattern,dendrite growth velocity,distribution of thermal gradient and stray grain.Based on the research methods proposed in this work,any substrate crystallographic orientation can be studied,and predicted stray grains distribution can be visualized.
