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

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<h5>introduction</h5>
 
<h5>introduction</h5>
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* XXX spin chain can be solved by [[Bethe ansatz]]
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<h5>summary</h5>
  
 
*  Hamiltonian of XXX spin chain with  anisotropic parameter <math>\Delta=1</math><br><math>\hat H = \sum_{j=1}^{N} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \sigma_j^z \sigma_{j+1}^z+1)</math><br>
 
*  Hamiltonian of XXX spin chain with  anisotropic parameter <math>\Delta=1</math><br><math>\hat H = \sum_{j=1}^{N} (\sigma_j^x \sigma_{j+1}^x +\sigma_j^y \sigma_{j+1}^y + \sigma_j^z \sigma_{j+1}^z+1)</math><br>
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* <math>A(312)</math> corresponds to the permutation <math>1\to3, 2\to1, 3\to2</math>
 
* <math>A(312)</math> corresponds to the permutation <math>1\to3, 2\to1, 3\to2</math>
 
*  n=2 case<br><math>A(12)=s_{21}</math><br><math>A(21)=-s_{12}</math><br>
 
*  n=2 case<br><math>A(12)=s_{21}</math><br><math>A(21)=-s_{12}</math><br>
*  n=3 case<br><math>A(123)=s_{21}s_{31}s_{32}</math><br><math>A(312)=s_{13}s_{23}s_{21}</math><br><math>A(231)=s_{32}s_{12}s_{13}</math><br>
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*  n=3 case<br><math>A(123)=s_{21}s_{31}s_{32}</math><br><math>A(312)=s_{13}s_{23}s_{21}</math><br><math>A(231)=s_{32}s_{12}s_{13}</math><br>  <br>
 
 
 
 
  
 
 
 
 
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<h5>Bethe ansatz equation</h5>
 
<h5>Bethe ansatz equation</h5>
  
<math>s_{jl}=1-2\Delta e^{ik_l}+ e^{ik_l+ik_j}=1-2e^{ik_l}+ e^{ik_l+ik_j}</math>
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<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>
  
 
<math>\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}</math>
 
<math>\exp(ik_jL)=(-1)^{n-1}\prod_{l=1, l\neq j}^{n}\frac{s_{l,j}}{s_{j,l}}</math>
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n=3
 
n=3
 
 
 
  
 
<math>\exp(ik_1L)=\frac{s_{2,1}s_{3,1}}{s_{1,2}s_{1,3}}</math>
 
<math>\exp(ik_1L)=\frac{s_{2,1}s_{3,1}}{s_{1,2}s_{1,3}}</math>
  
 
<math>\exp(ik_2L)=\frac{s_{1,2}s_{3,2}}{s_{2,1}s_{2,3}}</math>
 
<math>\exp(ik_2L)=\frac{s_{1,2}s_{3,2}}{s_{2,1}s_{2,3}}</math>
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<math>\exp(ik_3L)=\frac{s_{1,3}s_{2,3}}{s_{3,1}s_{3,2}}</math>
  
 
 
 
 
  
<math>\exp(ik_3L)=\frac{s_{1,3}s_{2,3}}{s_{3,1}s_{3,2}}</math>
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<h5>eigenvalues</h5>
  
 
 
 
 
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<h5 style="line-height: 3.428em; margin: 0px; color: rgb(34, 61, 103); font-family: 'malgun gothic',dotum,gulim,sans-serif; font-size: 1.166em; background-position: 0px 100%;">articles</h5>
 
<h5 style="line-height: 3.428em; margin: 0px; color: rgb(34, 61, 103); font-family: 'malgun gothic',dotum,gulim,sans-serif; font-size: 1.166em; background-position: 0px 100%;">articles</h5>
  
 
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*  Evaluation of Integrals Representing Correlations in XXX Heisenberg Spin Chain<br> Authors: H.E.Boos, V.E.Korepin<br>
 
 
 
* http://www.ams.org/mathscinet
 
* http://www.ams.org/mathscinet
 
* http://www.zentralblatt-math.org/zmath/en/
 
* http://www.zentralblatt-math.org/zmath/en/

2011년 1월 7일 (금) 06:29 판

introduction

 

 

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

 

review on spin system

spin system

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

 

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

 

 

 

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

 

 

 

history

 

 

related items

 

 

encyclopedia

 

 

books

 

 

 

expositions

 

 

articles

 

 

question and answers(Math Overflow)

 

 

blogs

 

 

experts on the field

 

 

links