Bipartite entanglement in spin-1/2 Heisenberg model

• Published in: Chinese physics C Vol. 32; no. 4; pp. 303 - 307
• Main Author: 胡明安 田东平
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.04.2008
• Subjects: 三旋模型; 二旋模型; 双向纠缠; 海森堡模型; 量子力学
• ISSN: 1674-1137; 0254-3052; 2058-6132
• DOI: 10.1088/1674-1137/32/4/013

The bipartite entanglement of the two- and three-spin Heisenberg model was investigated by using the concept of negativity. It is found that for the ground-state entanglement of the two-spin model, the negativity always decreases as B increases if △ 〈γ- 1, and it may keep a steady value of 0.5 in the region of B 〈 J[（△＋ 1）2 -γ^2]^1/2 if △ 〉γ-1, while for that of the three-spin model, the negativity exhibits square wave structures if γ=0 or△=0. For thermal states, there are two areas showing entanglement, namely, the main region and the sub-region. The main region exists only when △ 〉 △c （△c =γ- 1 and （γ^2 - 1）/2 for the 2- and 3-spin model respectively） and extends in terms of B and T as A increases, while the sub-region survives only when γ≠0 and shrinks in terms of B and T as △ increases.