Pairwise entanglement and local polarization of Heisenberg model  

作　　者：XI XiaoQiang1,2, ZHANG Tao3, YUE RuiHong3,4 & LIU WuMing2 1 Department of Applied Mathematics and Physics, Xi’an Institute of Post and Telecommunications, Xi’an 710061, China 2 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China 3 Institute of Modern Physics, Northwest University, Xi’an 710069, China 4 Department of Physics, Ningbo University, Ningbo 315211, China 

出　　处：《Science China(Physics,Mechanics & Astronomy)》2008年第10期1515-1522,共8页中国科学：物理学、力学、天文学（英文版）

基　　金：Supported by the National Natural Science Foundation of China (Grant Nos. 10547008, 90403034, 90403019, 90406017 and 60525417);the National Key Basic Research Special Foundation of China (Grant Nos. 2005CB724508 and 2006CB921400);the Foundation of Xi’an Institute of Post and Telecommunications (Grant No. 105-0414);the Natural Science Foundation of Shanxi Province (Grant No. 2004A15)

摘　　要：The characteristics of pairwise entanglement and local polarization (LP) are dis-cussed by studying the ground state (states) of the Heisenberg XX model. The re-sults show that: the ground state (states) is (are) composed of the micro states with the minimal polarization (0 for even qubit and 1/2 for odd qubit); LP and the prob-ability of the micro state have an intimate relation, i.e. the stronger the LP, the smaller the probability, and the same LP corresponds to the same probability; the pairwise entanglement of the ground state is the biggest in all eigenvectors. It is found that the pairwise entanglement is decreased by the state degeneracy and the system size. The concurrence approaches a fixed value of about 0.3412 (for odd-qubit chain) or 0.3491 (for even-qubit chain) if the qubit number is large enough.The characteristics of pairwise entanglement and local polarization (LP) are discussed by studying the ground state (states) of the Heisenberg XX model. The results show that: the ground state (states) is (are) composed of the micro states with the minimal polarization (0 for even qubit and 1/2 for odd qubit); LP and the probability of the micro state have an intimate relation, i.e. the stronger the LP, the smaller the probability, and the same LP corresponds to the same probability; the pairwise entanglement of the ground state is the biggest in all eigenvectors. It is found that the pairwise entanglement is decreased by the state degeneracy and the system size. The concurrence approaches a fixed value of about 0.3412 (for odd-qubit chain) or 0.3491 (for even-qubit chain) if the qubit number is large enough.

关 键 词：HEISENBERG XX MODEL LOCAL POLARIZATION pairwise ENTANGLEMENT 

分 类 号：O431.2[机械工程—光学工程]