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 or DensityMatrix 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)