Circuit Construction using IBM Quantum Composer

Question

I am trying to create the following circuit in IBM Quantum Composer but I cannot add the last H gate correctly. It falls in the wrong place. Why?

Answer 1

They are equivalent in the sense that they implement the same unitary.

But if you want to keep the alignment you can insert a barrier:

Note however that if you plan to run your circuits on actual quantum computer, in general barriers may affect the process of transpilation and execution. See here for details.

---

Update

In the new version of IBM Quantum Composer (now in beta) you can use freeform alignment to place gates anywhere in the composer: