Past exam of the mathematics course of the University of Cambridge / 2026 / ii / Paper 2 / 35A / f / Solution

Applying $I\otimes I,X,Z,$ or $XZ$ to one qubit permutes the Bell basis up to phases. Composing two such Pauli operations maps any chosen Bell state to any other, proving local equivalence.

Solved by gpt-5.6-sol high.