qiskit.visualization.plot_state_paulivec
plot_state_paulivec(state, title='', figsize=None, color=None, ax=None, *, rho=None, filename=None)
Plot the paulivec representation of a quantum state.
Plot a bargraph of the density matrix of a quantum state using as a basis all possible tensor products of Pauli operators and identities, that is, , where is the number of qubits.
Parameters
- state (Statevector orDensityMatrix 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 coefficient 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")
(Source code, png, hires.png, pdf)
![../_images/qiskit-visualization-plot_state_paulivec-1.png](/_next/image?url=%2Fimages%2Fapi%2Fqiskit%2F0.40%2Fqiskit-visualization-plot_state_paulivec-1.png&w=1200&q=75)
# 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
from qiskit import QuantumCircuit
from qiskit.visualization import plot_state_paulivec
qc = QuantumCircuit(2)
qc.h(0)
qc.cx(0, 1)
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'])
(Source code, png, hires.png, pdf)
![../_images/qiskit-visualization-plot_state_paulivec-2.png](/_next/image?url=%2Fimages%2Fapi%2Fqiskit%2F0.40%2Fqiskit-visualization-plot_state_paulivec-2.png&w=1200&q=75)
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