The Bloch Sphere
The Quantum Turtle · Quantum Play Lab
The Bloch Sphere
Explore quantum states in 3D. Turn the sphere, press a gate, and watch the qubit change.
QUANTUM PLAY LAB · BLOCH SPHERE
Choose a qubit state
Use two sliders to point the arrow anywhere on the sphere. Chance of 1 sets how often you may measure 1. Relative Phase turns the arrow around the sphere.
MEASURED RESULT
CHANCE OF 0 OR 1
Ready! Press X to flip the qubit.
Try this first
- Choose |0⟩. The arrow points up.
- Press H. The arrow moves to the middle. Now 0 and 1 each have a 50% chance.
- Press Z. The arrow turns, but the chances stay at 50/50.
- Press H again, then Measure. You will get 1.
Prefer the two-circle view? Try My First Qubit →
What the board shows
This board shows one qubit as an arrow inside a sphere. The arrow tells you its state. X, Y, and Z turn the arrow around different axes. H turns it around a slanted axis. Each gate follows the correct path. Drag the sphere to see the arrow from a new angle. This changes your view, not the qubit. Chance of 1 (θ) moves the arrow between the top and bottom. Relative Phase (φ) turns it around the middle. At the top or bottom, changing the phase does not change the state.
Measure a qubit to get 0 or 1. The result depends on its chances. After you measure, the qubit stays at that result until you change it with a gate or slider.