Qourse

Phase

Intermediate · 4 lessons · 17 activities

The half-turn no single measurement can see: where relative phase hides, why global phase is unobservable, the gates that turn it (Z, S, T and the rotations) — and the Bloch sphere, introduced here because this is where a third axis finally has a job to do.

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Lessons

  1. Relative phase

    Two states with identical measurement odds, told apart only by the angle between their amplitudes. Meet the dial that shows it and the gate that turns it.

    5 activities · 13 min

  2. Global phase is not a thing

    One phase in quantum computing genuinely does not exist. Learn which, why no experiment can ever find it, and why that makes the other kind of phase real.

    4 activities · 10 min

  3. The phase gates

    Z, S and T are the same rotation at three sizes: a half turn, a quarter, an eighth. Meet the family, and find out why one of them costs far more than the others.

    4 activities · 11 min

  4. Making phase visible

    Phase that no measurement can see becomes the answer once you interfere it. Watch an invisible half-turn turn into a certainty, and meet the third axis that finally has a job to do.

    4 activities · 12 min