qiskit.visualization.plot_bloch_multivector

plot_bloch_multivector(state, title='', figsize=None, *, rho=None, reverse_bits=False, filename=None)

Plot a Bloch sphere for each qubit.

Each component $(x,y,z)$ of the Bloch sphere labeled as ‘qubit i’ represents the expected value of the corresponding Pauli operator acting only on that qubit, that is, the expected value of $I_{N-1} \otimes\dotsb\otimes I_{i+1}\otimes P_i \otimes I_{i-1}\otimes\dotsb\otimes I_0$, where $N$ is the number of qubits, $P\in \{X,Y,Z\}$ and $I$ is the identity operator.

Parameters

• state (Statevector orDensityMatrix or ndarray) – an N-qubit quantum state.
• title (str) – a string that represents the plot title
• figsize (tuple) – Has no effect, here for compatibility only.
• reverse_bits (bool) – If True, plots qubits following Qiskit’s convention [Default:False].

Returns

A matplotlib figure instance.

Return type

matplotlib.Figure

Raises

• MissingOptionalLibraryError – Requires matplotlib.
• VisualizationError – if input is not a valid N-qubit state.

Examples

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
from qiskit.visualization import plot_bloch_multivector
 
qc = QuantumCircuit(2)
qc.h(0)
qc.x(1)
 
state = Statevector(qc)
plot_bloch_multivector(state)

(Source code, png, hires.png, pdf)

from qiskit import QuantumCircuit
from qiskit.quantum_info import Statevector
from qiskit.visualization import plot_bloch_multivector
 
qc = QuantumCircuit(2)
qc.h(0)
qc.x(1)
 
# You can reverse the order of the qubits.
 
from qiskit.quantum_info import DensityMatrix
 
qc = QuantumCircuit(2)
qc.h([0, 1])
qc.t(1)
qc.s(0)
qc.cx(0,1)
 
matrix = DensityMatrix(qc)
plot_bloch_multivector(matrix, title='My Bloch Spheres', reverse_bits=True)

(Source code, png, hires.png, pdf)