"Heisenberg spin1/2 XXX chain"의 두 판 사이의 차이

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7번째 줄: 7번째 줄:
 
 
 
 
  
<h5>summary</h5>
+
<h5>review on spin system</h5>
  
* Hamiltonian of XXX spin chain with  anisotropic parameter <math>\Delta=1</math><br><math>\hat H = \sum_{j=1}^{L} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \sigma_j^z \sigma_{j+1}^z+1)</math><br>
+
* [[spin system and Pauli exclusion principle|spin system]]<br>
*  two body scattering term<br><math>s_{j,l}=1-2\Delta e^{ik_l}+ e^{ik_l+ik_j}=1-2e^{ik_l}+ e^{ik_l+ik_j}</math><br>
+
*  raising and lowering operators<br><math>\sigma_{\pm}=\frac{1}{2}(\sigma_{x}\pm i\sigma_{y})</math><br><math>\sigma_{+}=\frac{1}{2}(\sigma_{x}+ i\sigma_{y})=\begin{pmatrix} 0&1\\ 0&0 \end{pmatrix}</math><br><math>\sigma_{-}=\frac{1}{2}(\sigma_{x}- i\sigma_{y})=\begin{pmatrix} 0&0\\ 1&0 \end{pmatrix}</math><br><math>[\sigma_{z},\sigma_{\pm}]=\pm 2\sigma_{\pm}</math><br>
*  phase shift term <math>\theta(p,q)</math><br><math>\exp(-i\theta(k_j,k_l))=\frac{s_{l,j}}{s_{j,l}}=\frac{1-2\Delta e^{ik_j}+e^{i(k_j+k_l)}}{1-2\Delta e^{ik_l}+e^{i(k_j+k_l)}}</math><br>
 
*  equation satisfied by wave numbers<br><math>\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}=(-1)^{n-1}\prod_{l=1}^{L}\exp(-i\theta(k_j,k_l))</math><br>
 
*  fundamental equation<br><math>k_jN=2\pi I(k_j)+\sum_{l=1}^{N}\theta(k_j,k_l)</math><br>
 
  
 
 
 
 
  
<h5>review on spin system</h5>
+
<math>h=\frac{\sigma_{i}\cdot\sigma_{j}+1}{2}</math> acts as the permutation operator
  
* [[spin system and Pauli exclusion principle|spin system]]<br>
+
 
*  raising and lowering operators<br><math>\sigma_{\pm}=\frac{1}{2}(\sigma_{x}\pm i\sigma_{y})</math><br><math>\sigma_{+}=\frac{1}{2}(\sigma_{x}+ i\sigma_{y})=\begin{pmatrix} 0&1\\ 0&0 \end{pmatrix}</math><br><math>\sigma_{-}=\frac{1}{2}(\sigma_{x}- i\sigma_{y})=\begin{pmatrix} 0&0\\ 1&0 \end{pmatrix}</math><br><math>[\sigma_{z},\sigma_{\pm}]=\pm 2\sigma_{\pm}</math><br>
 
  
 
 
 
 
  
<math>h=\frac{\sigma_{i}\cdot\sigma_{j}+1}{2}</math> acts as the permutation operator
+
<h5>summary</h5>
 +
 
 +
*  Hamiltonian of XXX spin chain with  anisotropic parameter <math>\Delta=1</math><br><math>\hat H = \sum_{j=1}^{L} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \sigma_j^z \sigma_{j+1}^z+1)</math><br>
 +
*  two body scattering term<br><math>s_{j,l}=1-2\Delta e^{ik_l}+ e^{ik_l+ik_j}=1-2e^{ik_l}+ e^{ik_l+ik_j}</math><br>
 +
*  phase shift term <math>\theta(p,q)</math><br><math>\exp(-i\theta(k_j,k_l))=\frac{s_{l,j}}{s_{j,l}}=\frac{1-2\Delta e^{ik_j}+e^{i(k_j+k_l)}}{1-2\Delta e^{ik_l}+e^{i(k_j+k_l)}}</math><br>
 +
*  equation satisfied by wave numbers<br><math>\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}=(-1)^{n-1}\prod_{l=1}^{L}\exp(-i\theta(k_j,k_l))</math><br>
 +
*  fundamental equation<br><math>k_jN=2\pi I(k_j)+\sum_{l=1}^{N}\theta(k_j,k_l)</math><br>
  
 
 
 
 
142번째 줄: 144번째 줄:
  
 
* [http://pos.sissa.it/archive/conferences/038/006/Solvay_006.pdf XXX Spin Chain: from Bethe Solution to Open Problems]
 
* [http://pos.sissa.it/archive/conferences/038/006/Solvay_006.pdf XXX Spin Chain: from Bethe Solution to Open Problems]
 
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* [http://arxiv.org/abs/cond-mat/9509183 Bethe Ansatz for Heisenberg XXX Model] Authors: Shao-shiung Lin, Shi-shyr Roan
 
 
  
 
 
 
 

2011년 1월 13일 (목) 09:49 판

introduction

 

 

review on spin system
  • spin system
  • raising and lowering operators
    \(\sigma_{\pm}=\frac{1}{2}(\sigma_{x}\pm i\sigma_{y})\)
    \(\sigma_{+}=\frac{1}{2}(\sigma_{x}+ i\sigma_{y})=\begin{pmatrix} 0&1\\ 0&0 \end{pmatrix}\)
    \(\sigma_{-}=\frac{1}{2}(\sigma_{x}- i\sigma_{y})=\begin{pmatrix} 0&0\\ 1&0 \end{pmatrix}\)
    \([\sigma_{z},\sigma_{\pm}]=\pm 2\sigma_{\pm}\)

 

\(h=\frac{\sigma_{i}\cdot\sigma_{j}+1}{2}\) acts as the permutation operator

 

 

summary
  • Hamiltonian of XXX spin chain with  anisotropic parameter \(\Delta=1\)
    \(\hat H = \sum_{j=1}^{L} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \sigma_j^z \sigma_{j+1}^z+1)\)
  • two body scattering term
    \(s_{j,l}=1-2\Delta e^{ik_l}+ e^{ik_l+ik_j}=1-2e^{ik_l}+ e^{ik_l+ik_j}\)
  • phase shift term \(\theta(p,q)\)
    \(\exp(-i\theta(k_j,k_l))=\frac{s_{l,j}}{s_{j,l}}=\frac{1-2\Delta e^{ik_j}+e^{i(k_j+k_l)}}{1-2\Delta e^{ik_l}+e^{i(k_j+k_l)}}\)
  • equation satisfied by wave numbers
    \(\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}=(-1)^{n-1}\prod_{l=1}^{L}\exp(-i\theta(k_j,k_l))\)
  • fundamental equation
    \(k_jN=2\pi I(k_j)+\sum_{l=1}^{N}\theta(k_j,k_l)\)

 

 

 

wavefunction amplitude
  • amplitudes \(A(P)\) satisfies
    \(A_{P}=\sigma_{P}\prod_{1\leq i< j\n}s_{P_{j}P_{i}}\), where \(\sigma_{P}\) = sign of the permutation
  • \(A(312)\) corresponds to the permutation \(1\to3, 2\to1, 3\to2\)
  • n=2 case
    \(A(12)=s_{21}\)
    \(A(21)=-s_{12}\)
  • n=3 case
    \(A(123)=s_{21}s_{31}s_{32}\)
    \(A(312)=s_{13}s_{23}s_{21}\)
    \(A(231)=s_{32}s_{12}s_{13}\)
     

 

Bethe ansatz equation

\(s_{j,l}=1-2\Delta e^{ik_l}+ e^{ik_l+ik_j}=1-2e^{ik_l}+ e^{ik_l+ik_j}\)

\(\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}\)

n=1

\(\exp(ik_jL)=1\)

n=2

\(\exp(ik_1L)=-\frac{s_{2,1}}{s_{1,2}}=-\frac{1-2e^{ik_1}+ e^{ik_1+ik_2}}{1-2e^{ik_2}+ e^{ik_1+ik_2}}\)

\(\exp(ik_2L)=-\frac{s_{1,2}}{s_{2,1}}=-\frac{1-2e^{ik_2}+ e^{ik_1+ik_2}}{1-2e^{ik_1}+ e^{ik_1+ik_2}}\)

 

n=3

\(\exp(ik_1L)=\frac{s_{2,1}s_{3,1}}{s_{1,2}s_{1,3}}\)

\(\exp(ik_2L)=\frac{s_{1,2}s_{3,2}}{s_{2,1}s_{2,3}}\)

\(\exp(ik_3L)=\frac{s_{1,3}s_{2,3}}{s_{3,1}s_{3,2}}\)

 

 

 

eigenvalues

 

 

emptiness formation probability

 

 

 

near neighbor correlations

 

 

 

 

history

 

 

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