Incorrect Hamiltonian for max cut problem graph in `Variational Algorithm Design` badge

[GuillermoAbadLopez]

URL to the relevant documentation

Max cut problem in Ansatze and Variational Forms of the Variational Algorithm Design badge

Select all that apply

• [X] typo (typo but in IBM Quantum Learning)

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Problem

Hey! I was doing the Variational Algorithm Design badge, from IBM Quantum learning, and I noticed that in the max-cut problem, the SparsePauliOp that is given as a Hamiltonian, looked a bit off:

(notice the Z's positions in each term [from right to left], indicate an edge (the connectivity) between two nodes: IIZZ means there are 4 qubits, and that qubit 0 is connected to qubit 1)

Possible origin of the Problem

I think this comes from a copypaste from this other graph in another page, where its actually correct (different graph)

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Solution

This IIIZZ+IIZIZ+IZIIZ+ZIIIZ, has to change into IIZZ+IZIZ+IZZI+ZIIZ+ZZII, both in:

• [ ] the text
• [ ] and in the code-block under

(or the graph image has to change, but that would be weird, since in the next page we use it...)

Checks:

I searched a bit, and found this old documentation, from Qiskit textbook, which has what I would have guessed is correct:

Also, a bit later, I arrived at the next page of the Badge (Cost Functions), and there it was correctly written as well:

[GuillermoAbadLopez]

Opening the Issue here, since I didn't know where else to open it..

@Eric-Arellano told me that later, he would tag the relevant people 👍