Bogoliubov transformation
= Bogoliubov transformation
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A <Bogoliubov transformation> is a <canonical transformation of mode operators> mixing <creation operators> and <annihilation operators>. It diagonalizes quadratic <Hamiltonians> or relates different vacuum descriptions. Bosonic and fermionic canonical bracket constraints differ. A nonzero creation-mixing coefficient makes its vacuum contain particles relative to the original mode decomposition.