Bloch-sphere viewer (quantum_mind.viz)

See qubits move in 3D: gate by gate through any Qiskit circuit, event by event through a quantum-like trust model, or as measured on a simulator or quantum hardware.

Function	Output	Needs
bloch_vector(state), bloch_vectors(state)	Bloch vectors of one qubit or every qubit (reduced states of entangled qubits lie inside the ball)	NumPy
circuit_trajectory(qc, steps)	Trajectory: each gate applied in fractional steps U^(k/steps), so rotations draw arcs	Qiskit
belief_trajectory(model, events)	Trajectory of the belief qubit of OpenSystemBelief (rotation, then dephasing)	NumPy
bloch_tomography(qc, backend, shots)	Bloch vectors estimated from X, Y, Z measurements on aer, aer:FakeTorino, ibm:…, braket:…	Qiskit (+ backend)
plot_bloch(vectors), BlochSphere	Static Matplotlib figure; add vectors, points, trajectories	Matplotlib
animate_trajectory(traj, save='x.gif')	Matplotlib animation; GIF (Pillow) or MP4 (ffmpeg); optional camera rotation	Matplotlib
bloch_figure(vectors)	Interactive Plotly figure (rotate, zoom, hover)	Plotly
animate_bloch(traj) + save_html(fig, path)	Interactive animation with play/pause and a labelled slider; standalone HTML	Plotly
LiveBloch(n).show(); .update(state); .play(traj)	Real-time spheres: a Plotly FigureWidget in Jupyter, a Matplotlib window elsewhere	Plotly + ipywidgets + anywidget, or Matplotlib
concurrence(rho), entanglement_summary(state), traj.concurrence(a, b)	Pairwise entanglement (Wootters concurrence; checked against Qiskit) and Bloch-vector lengths	NumPy
plot_entanglement(traj)	Timeline of Bloch lengths and concurrence along a circuit, labelled by gate	Matplotlib
plot_qsphere(state)	Q-sphere of a multi-qubit state (Qiskit’s plot_state_qsphere)	Qiskit, Matplotlib, seaborn

from qiskit import QuantumCircuit
from quantum_mind.viz import circuit_trajectory, animate_bloch, save_html, animate_trajectory, LiveBloch

qc = QuantumCircuit(2); qc.h(0); qc.cx(0, 1); qc.ry(0.6, 1)
traj = circuit_trajectory(qc, steps=15)
save_html(animate_bloch(traj, title='Bell state'), 'bell.html')     # open in a browser
animate_trajectory(traj, save='bell.gif', rotate=0.5)              # for slides and READMEs

live = LiveBloch(2).show()          # Jupyter: an interactive widget that updates in place
live.play(traj, fps=30)             # or call live.update(state) inside a simulation loop

Themes. theme='dark' (default, GitHub dark palette) or 'light', or a dict with the keys of quantum_mind.viz.THEMES['dark'].

Conventions. Qiskit qubit order (qubit q is bit q of the basis index); |0⟩ at the north pole, |+⟩ on +x, |+i⟩ on +y. In the trust model, the north pole means “yes, I trust the robot”.

Relation to Qiskit’s own plots. qiskit.visualization.plot_bloch_multivector draws one static state. quantum_mind.viz adds trajectories through a circuit, animation, interactive HTML, live updating and tomography from real backends; it accepts Qiskit Statevector and DensityMatrix objects directly.