I could find from this source -- but also from other works on ZX-calculus -- the following extract:

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This looks to me as a generalisation of a 2-qubit Ising gate to an $n$-qubit global Ising gate. Especially considering that the 2-qubit case admits the following synthesis:

enter image description here

I find global gates particularly interesting, hence I am intrigued by the compactness of this representation, both mathematical and graphical.

Is my statement correct, namely, that this representation is a generalised Ising gate?

  • 2
    $\begingroup$ Yes a phase gadget (which is a CNOT ladder, then a phase, and another CNOT ladder) implements $e^{-i \alpha/2 Z\otimes \cdots \otimes Z}$ and in that sense it is a generalisation of the Ising interaction. $\endgroup$
    – John
    Aug 14, 2023 at 15:20


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