Relative phase bug on plot_state_qsphere

[jvscursulim]

Environment

• Qiskit version: 1.3.2
• Python version: 3.11.10
• Operating system: Ubuntu 24.04.1 LTS

What is happening?

I was using the function plot_state_qsphere to inspect if the state that I was preparing with my quantum circuit was right, but what I saw it was the relative phase in the wrong state, like in the image attached to this comment. I took a look in the plot_state_qsphere function, and I saw that the class DensityMatrix is used, so I decided to check if the density matrix was correct and it was correct, then I think that must be a problem in the plot preparation.

How can we reproduce the issue?

from qiskit.circuit import QuantumCircuit
from qiskit.visualization import plot_state_qsphere

qc = QuantumCircuit(2)

qc.x(qubit=0)
qc.h(qubit=0)
qc.cx(control_qubit=0, target_qubit=1)

plot_state_qsphere(qc)

What should happen?

The phase $e^{i\pi} = -1$ should appears on the state $\vert 11 \rangle$.

Any suggestions?

No response

[jakelishman]

See #10029 (comment) for the detail.

I'm not opposed to somebody providing a PR to change the default behaviour, if desired.