garden/tensor-product.md
2025-09-24 10:24:30 -06:00

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Tensor Product

  • cartesian-product
  • kronecker-product
  • on two quantum-states:
    • take the cartesian product of the set of component states, this is the new set of states
    • the scalar attached to each new state is the product of the two component scalars
    • `\left(\alpha\ket{0}+\beta\ket{1}\right)\otimes\left(\gamma\ket{0}+\delta\ket{1}\right) = \alpha\gamma\ket{00} + \alpha\delta\ket{01} + \beta\gamma\ket{10} + \beta\delta\ket{11}`
  • on two unitary-operators:
    • `\mathbf{A} \otimes \mathbf{B} = \begin{bmatrix} a_{11}\mathbf{B} & \cdots & a_{1n}\mathbf{B} \\ \vdots & \ddots & \vdots \\ a_{m1} \mathbf{B} & \cdots & a_{mn} \mathbf{B} \end{bmatrix}`
  • `\left(\mathbf{A} \otimes \mathbf{B}\right)\left(\mathbf{C} \otimes \mathbf{D}\right) = \mathbf{A}\mathbf{C} \otimes \mathbf{B}\mathbf{D}`