标题： 长程量子自旋链无序或无无序情况下最简单的非均匀和均匀树张量态的性质 显示英文标题

标题： Properties of the simplest inhomogeneous and homogeneous Tree-Tensor-States for Long-Ranged Quantum Spin Chains with or without disorder

摘要： 研究了满足宇称和时间反演对称性的最简单的树张量态（TTS），以描述长程量子自旋链在有无无序情况下的基态。给出了单点和两点约化密度矩阵的显式公式，从而可以计算任何单自旋和双自旋可观测量。对于仅包含单体和双体贡献的哈密顿量，可以计算并最小化TTS的能量，以获得TTS的最佳参数。这种TTS参数的变分优化与基于某些块内约化哈密顿量对角化的传统块自旋重正化过程进行了比较。 显示英文摘要

摘要： The simplest Tree-Tensor-States (TTS) respecting the Parity and the Time-Reversal symmetries are studied in order to describe the ground states of Long-Ranged Quantum Spin Chains with or without disorder. Explicit formulas are given for the one-point and two-point reduced density matrices that allow to compute any one-spin and two-spin observable. For Hamiltonians containing only one-body and two-body contributions, the energy of the TTS can be then evaluated and minimized in order to obtain the optimal parameters of the TTS. This variational optimization of the TTS parameters is compared with the traditional block-spin renormalization procedure based on the diagonalization of some intra-block renormalized Hamiltonian.