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Level 1 · Geometry · Unit 2 of 4

Gates turn the arrow

about 7 min · Free · No sign-in needed

A gate moves the arrow without changing its length, because the probabilities must still add up to 1. On this circle, X and H are mirror flips. X mirrors the arrow across the 45° line, which swaps the amplitudes of 0 and 1. H mirrors it across the 22.5° line, taking 0° to 45° and 90° to −45°.

  1. 1. Predict
  2. 2. Run
  3. 3. Rules
  4. 4. Redraw
  5. 5. Explain
  6. 6. Done

Prediction 1 of 2

Simulated

Predict first, then run it.

|0⟩|1⟩−|0⟩−|1⟩

0° → H → H → ?

Arrow angle ? · Amplitude of 0 ? · Amplitude of 1 ?

Probability of 0?
Probability of 1?
The arrow starts at 0°, the state 0. Apply H twice. Where does it end up?

Clears this unit's progress and drawing record on this device.