Local Entanglement and quantum phase transition in spin models

Due to the phase interference of electromagnetic wave, one can recover the total image of one object from a small piece of holograph, which records the interference pattern of two laser light reflected from it. Similarly, the quantum superposition principle allows us to derive the global phase diagram of quantum spin models by investigating a proper local measurement. In the present paper, we study the two-site entanglement in the antifferomagnetic spin models with both spin-1/2 and 1. We show that its behaviors reveal some important information on the global properties and the quantum phase transition of these systems.Comment: 6 pages, 7 figure

Observation of Quantized Hall Effect and Shubnikov-de Hass Oscillations in Highly Doped Bi2Se3: Evidence for Layered Transport of Bulk Carriers

Bi2Se3 is an important semiconductor thermoelectric material and a prototype topological insulator. Here we report observation of Shubnikov-de Hass (SdH) oscillations accompanied by quantized Hall resistances (Rxy) in highly-doped n-type Bi2Se3 with bulk carrier concentrations of few 10^19 cm^-3. Measurements under tilted magnetic fields show that the magnetotransport is 2D-like, where only the c-axis component of the magnetic field controls the Landau level formation. The quantized step size in 1/Rxy is found to scale with the sample thickness, and average ~e2/h per quintuple layer (QL). We show that the observed magnetotransport features do not come from the sample surface, but arise from the bulk of the sample acting as many parallel 2D electron systems to give a multilayered quantum Hall effect. Besides revealing a new electronic property of Bi2Se3, our finding also has important implications for electronic transport studies of topological insulator materials.Comment: accepted by Physical Review Letters (2012

Entanglement and quantum phase transitions

We examine several well known quantum spin models and categorize behavior of pairwise entanglement at quantum phase transitions. A unified picture on the connection between the entanglement and quantum phase transition is given.Comment: 4 pages, 3 figure

Horndeski Gravity and the Violation of Reverse Isoperimetric Inequality

We consider Einstein-Horndeski-Maxwell gravity, together with a cosmological constant and multiple Horndeski axions. We construct charged AdS planar black holes in general dimensions where the Horndeski anxions span over the planar directions. We analyse the thermodynamics and obtain the black hole volumes. We show that the reverse isoperimetric inequality can be violated, implying that these black holes can store information more efficiently than the Schwarzschild black hole.Comment: Latex, 25 pages, 1 figure, references adde

A Predictive Analysis on Group Exercise of Chinese Rhythmic Gymnastics at the 2008 Olympic

This article has conducted a compared analysis on skills of top 6 teams at the 2006 and 2007 World Rhythmic Gymnastics Championships, and “Luck Beijing” International Invitation Match by using documents, video tapes, and statistic methods. The results show that the Chinese team has already been in the position of first level in the World and has a potential capability to be in the top 3 teams at the 2008 Olympic. However, the quality of skill execution, skill value, and art value need to be improved and renovated. Keyword: Rhythmic gymnastics, group exercise, the 29th Olympics, China, skill strength, foreground Résumé: En utilisant plusieurs méthodes de recherche, notamment en étudiant des documentations, des vidéo et des statistiques, on a fait des analyses et des comparaisions sur la technique des six premières équipes de la Coupe du monde 2006, du Championnat international de 2007 et du Tournoi international à invitation de “Good Luck Beijing“, dont le résultat montre bien que l’équipe chinoise s’est qualifiée parmi les équipes les plus compétentes du monde et qu’elle a la possibilité de gagner une médaille aux Jeux Olympiques. Pourtant, il faut faire attention à la qualité de l’semble des mouvements, à la valeur technique et artistique. Mots-clés: gymnastique rythmique, compétition en équipe, 29ème Jeux Olympiques, Chine, niveau technique, perspective 摘 要: 通過文獻資料、錄影、數理統計與比較研究方法，對2006年藝術體操世界盃系列賽、2007年世界錦標賽和“好運北京”國際邀請賽集體項目前六名隊伍的技術進行比較分析，結果表明：中國藝術體操集體項目已具有世界一流水平和爭奪 08年奧運會前3名的實力，但是，在成套動作完成品質、技術價值和藝術價值方面有待進一步加強和突破。 關鍵詞: 藝術體操；集體專案；29屆奧運會；中國；技術實力；前