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Quantum Circuit Simulator — Multi-Qubit Gates & Bloch Sphere, Interactive

Build a multi-qubit quantum circuit by placing real quantum logic gates — Hadamard, Pauli-X/Y/Z, CNOT and more — and watch the resulting complex state amplitudes update as you go, visualised on an interactive 3D Bloch sphere for single-qubit intuition. It is a genuine state-vector simulation of the circuit you build, not a static diagram.

How to use Quantum Circuit & Bloch Sphere Sandbox

1. Add qubits and place gates on the circuit.
2. Watch the state amplitudes update after each gate.
3. Rotate the 3D Bloch sphere to see single-qubit state visually.
4. Try a preset — superposition, entanglement via CNOT, or a simple algorithm.

Frequently asked questions

What does the Bloch sphere actually represent?

A geometric way to visualise a single qubit's state as a point on a unit sphere — the north and south poles are the classical |0⟩ and |1⟩ states, and any point in between represents a quantum superposition of the two.

Is this a real quantum simulation or an illustration?

It is a real classical simulation of quantum state evolution — it computes actual complex amplitudes as gates are applied, the standard way to simulate small quantum circuits on classical hardware, not a static explainer diagram.

How does entanglement show up here?

Applying a CNOT gate to a qubit in superposition entangles it with the target qubit — you can see the resulting joint state can no longer be described as two independent single-qubit states, which the amplitude display makes visible.

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