Past exam of the computer science course of the University of Oxford / 2021 / Quantum information / 1 / c / i

Prepare Bob in $|0{⟩}_B$ and encode the bit using Alice's preparation $|m{⟩}_A$. The controlled-NOT gate givesBob measures in the computational basis and reads $m$ with probability one. Alice's final measurement is unnecessary. The interaction transmits a classical bit; it does not clone an arbitrary unknown qubit.