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## TriangularOperatorsA ## ConstructionThe main method of constructing a triangular operator is via It is possible to construct triangular operators that act on a larger unit cell, via an optional parameter ## Finite momentumIt is possible to also construct operators at finite momentum, for example {$X_k = \sum_n e^{-ikn} X(n)$} This is done with the function ## Kink operatorsA kink operator is a generalization of a momentum operator. For example, a string correlation can be written as an ordinary correlation of kink operators. Kink operators are also generated implicitly by fermion operators.
## ExpressionsIf `a*A` , where`a` is a scalar`A+B` `A*B` `[A,B]` `A^2` `A^N` , where`N` is an integer. This is calculated by repeated squaring.- inner(A,B) -- equivalent to
`dot(adjoint(A),B)` . - dot(A,B)
- conj(A)
- adjoint(A)
`cross(A,B)` -- only if`A` and`B` are {$SU(2)$} spin-1 vector operators.`outer(A,B)` -- outer product, only useful for non-abelian operators.
Addition of a triangular operator and a scalar is not defined. Nor is addition or multiplication of a triangular operator and a finite or product operator. |

Page last modified on September 14, 2020, at 10:08 AM