Math
Teleportation, and what the two classical bits are for
Alice's station holds a message qubit and half of a shared pair; Bob's holds the other half. Walk the protocol step by step - CNOT, H, measurement - and send the two bits down an ordinary channel. Stop them before they arrive and try to guess them; then pick Bob's correction and compare what he holds with the message. Until the bits arrive Bob's qubit is I/2 whatever was sent, and after measuring Alice keeps no copy.
What happens
Alice holds a qubit in some state and half of an entangled pair; Bob holds the other half. She entangles her qubit with her half, measures both and gets two bits - each of the four results with probability exactly 1/4, whatever the state was. Bob's qubit is now the state up to one of four corrections, and the bits name which. Until they reach him, over an ordinary channel at an ordinary speed, his qubit by itself is I/2 - the centre of the sphere - for every message. Alice's qubits, once read, sit at the poles her bits name: the state was moved, not copied.
Equations used in the module
Equations
|ψ⟩ = cos(t/2)|0⟩ + e^{if} sin(t/2)|1⟩
shared pair: H, CNOT; Alice: CNOT, H, measure two bits
Bob: X^{m₁} then Z^{m₀} → fidelity 1 for every outcome
without the bits: average fidelity ½, Bloch vector 0
