# Tag Info

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### Rxx gate as a set of rotations

Finally I found the answer. Bloch sphere coincides with a qubit only before the first controlled operation. After that Bloch sphere shows a "probability", while the real 3D-position of the ...
1 vote

### Rxx gate as a set of rotations

Why Qiskit shows the arrows shorter? Is it a bug or a feature (partially entangled states)? The arrows are shorter because of entanglement. This behavior is described in Qiskit's textbook[1]. One ...
• 3,930
1 vote

### Find a set of vectors on the Bloch sphere such that $\langle \psi_i | \psi_j \rangle = \frac{1}{\sqrt{n}}$

Essentially, you're given the Gram matrix $G$ ($G_{ii} = 1$, $G_{ij} = \frac{1}{\sqrt{n}}, i\neq j$) for a set of vectors. You can realize the vectors as columns of the square root of it, $\sqrt{G}$, ...
• 5,423

### Find a set of vectors on the Bloch sphere such that $\langle \psi_i | \psi_j \rangle = \frac{1}{\sqrt{n}}$

You do this iteratively. Start with $$|\psi_1\rangle=|0\rangle.$$ Then, one component of $|\psi_2\rangle$ is fixed to get the correct inner product, so add one more component with an amplitude set ...
• 46.1k
Accepted

### When using Qiskit's plot_bloch_vector function, how can I set colors for vectors?

A simple way to do that is by using Bloch class[1] directly which accepts a list of vector colors to cycle through: ...
• 3,930
1 vote

### Are qubits just analog, continuous classical bits?

Another point of view for this could be a complexity one. Namely, we know how to efficiently simulate analog computation classically. Whereas we still haven’t figured out how to do so for quantum ...
1 vote

### Are qubits just analog, continuous classical bits?

I consider only one qubit in this explanation. A qubit does not contain as much information as a "continuous classical needle" living in a sphere, in the following sense. If I assume that it ...

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