First order quantum phase transitions in the XX spin chain

2007/01/08 by Feng Pan, Nan Ma, Pan, Feng +5
Physics and Astronomy · #FOS: Physical sciences #Opinion Dynamics and Social Influence #Quantum Physics (quant-ph) #quant-ph

paper · pdf · doi:10.48550/arxiv.quant-ph/0701028

5 pages and 1 figure, LaTeX. More typos corrected; more refs added

openalex publication_date 2007/01/08 · arxiv created 2007/02/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Quantum phase transitional behavior of a finite periodic XX spin-1/2 chain with nearest neighbor interaction in a uniform transverse field is studied based on the simple exact solutions. It is found that there are [N/2] level-crossing points in the ground state, where N is the periodic number of the system and [x] stands for the integer part of x, when the interaction strength and magnitude of the magnetic field satisfy certain conditions. The quantum phase transitions are of the first order due to the level-crossing. The ground state in the thermodynamic limit will be divided into three distinguishable quantum phases.

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