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qiskit.visualization.plot_state_paulivec¶

plot_state_paulivec(state, title='', figsize=None, color=None, ax=None, *, rho=None, filename=None)[source]

Plot the paulivec representation of a quantum state.

Plot a bargraph of the mixed state rho over the pauli matrices

Parameters
• state (Statevector or DensityMatrix or ndarray) -- an N-qubit quantum state.

• title (str) -- a string that represents the plot title

• figsize (tuple) -- Figure size in inches.

• color (list or str) -- Color of the expectation value bars.

• ax (matplotlib.axes.Axes) -- An optional Axes object to be used for the visualization output. If none is specified a new matplotlib Figure will be created and used. Additionally, if specified there will be no returned Figure since it is redundant.

Returns

The matplotlib.Figure of the visualization if the `ax` kwarg is not set

Return type

matplotlib.Figure

Raises
• MissingOptionalLibraryError -- Requires matplotlib.

• VisualizationError -- if input is not a valid N-qubit state.

Examples

```# You can set a color for all the bars.

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
from qiskit.visualization import plot_state_paulivec

qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)

state = Statevector(qc)
plot_state_paulivec(state, color='midnightblue', title="New PauliVec plot")
```
```# If you introduce a list with less colors than bars, the color of the bars will
# alternate following the sequence from the list.

import numpy as np
from qiskit.quantum_info import DensityMatrix

qc = QuantumCircuit(2)
qc.h([0, 1])
qc.cz(0, 1)
qc.ry(np.pi/3, 0)
qc.rx(np.pi/5, 1)

matrix = DensityMatrix(qc)
plot_state_paulivec(matrix, color=['crimson', 'midnightblue', 'seagreen'])
```