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Analysis of entropy of XY Spin Chain

F. Franchini·A. R. Its·B. -Q. Jin·V. E. Korepin
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Abstract

Entanglement in the ground state of the XY model on the infinite chain can be measured by the von Neumann entropy of a block of neighboring spins. We study a double scaling limit: the size of the block is much larger then 1 but much smaller then the length of the whole chain. In this limit, the entropy of the block approaches a constant. The limiting entropy is a function of the anisotropy and of the magnetic field. The entropy reaches minima at product states and increases boundlessly at phase transitions.

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F. Franchini, A. R. Its, B. -Q. Jin, V. E. Korepin. 2006-06-29. Analysis of entropy of XY Spin Chain. https://arxiv.org/abs/quant-ph/0606240

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