Quantum Sandbox

Drag-and-drop circuits with gate-by-gate animation, entanglement meters, a Q-sphere, and live Qiskit code.

Build: drag an operation onto a wire (or click to arm, then click a cell). Many operations share a column across different wires.

Animate: press Play to sweep through the circuit gate by gate. Rotation gates follow a smooth geodesic; entangling gates make each qubit's Bloch vector shrink toward the centre as entanglement forms. Export the animation as a video.

Entanglement: each qubit's mini Bloch sphere shrinks as it becomes entangled (vector length = purity); the S meter is its von-Neumann entropy; pink bonds show pairwise concurrence. A product state keeps full vectors and no bonds; a Bell pair collapses two vectors and lights a bond; a GHZ state collapses all vectors with no bonds (genuine multipartite entanglement).

Q-sphere & code: node size ∝ probability, colour = phase (≤5 qubits). The exact Qiskit program is generated live in Qiskit little-endian order, so results match IBM Quantum.

Operations (30)

Single-qubit

Parametric

Controlled

Multi-qubit

Operations

Qubits: 3
q[0]
|0⟩
q[1]
|0⟩
q[2]
|0⟩
step 0/0

Animation Stage

Entanglement

Product state — no entanglement

Bloch vector length = purity (shrinks with entanglement). S = von Neumann entropy (0 = unentangled, 1 = maximal). Pink bonds = pairwise concurrence.

Q-sphere

node size ∝ probabilitycolour = phase

Statevector

Computational basis (q[2]…q[0]) at the current playhead.

|000⟩
100.0%0°

Qiskit code

from qiskit import QuantumCircuit
import numpy as np

qc = QuantumCircuit(3)