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Beginner10 min read

Superposition & Measurement

Measurement is not a passive reading. It is the most violent thing you can do to a quantum state.

Before this: What Is a Qubit?

In this lesson you’ll learn

  • Apply the Born rule to predict measurement statistics
  • Explain what collapse does to a state and why it is irreversible
  • Distinguish a coherent superposition from a probabilistic mixture

Recall before you read on

A qubit is prepared in the state (1/√3)|0⟩ + √(2/3)·|1⟩ and measured once in the computational basis. What is the probability the outcome is 1?

Commit to an answer — the next section is the payoff.