The Mermin-Wagner Theorem - Condensed Matter Theory Group
The Mermin-Wagner Theorem - Condensed Matter Theory Group
The Mermin-Wagner Theorem - Condensed Matter Theory Group
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How symmetry breaking occurs in principle<br />
Actors<br />
Proof of the <strong>Mermin</strong>-<strong>Wagner</strong> <strong>The</strong>orem<br />
Discussion<br />
<strong>The</strong> Bogoliubov inequality<br />
<strong>The</strong> <strong>Mermin</strong>-<strong>Wagner</strong> <strong>The</strong>orem<br />
To find a simple upper bound we may add to the right-hand side<br />
the same expression with k replaced by −k:<br />
[C, H] , C †<br />
<br />
−<br />
≤ 4 2 b z −iKRp Sp e<br />
+ 4<br />
p<br />
<br />
2<br />
m,p<br />
Jmp (1 − cos (k (Rm − Rp))) SmSp + S z mS z p<br />
Andreas Werner <strong>The</strong> <strong>Mermin</strong>-<strong>Wagner</strong> <strong>The</strong>orem
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