Mixed-Basis Readout

To estimate an observable like X (x) Z (x) Y, each qubit has to be measured in its own Pauli basis. Hardware can only measure Z, so rotate first.

Objective

basis_readout(bases) receives a string over {X, Y, Z} (rightmost character = qubit 0) and returns a circuit that maps each qubit's +1 eigenstate of its Pauli to |0> and its -1 eigenstate to |1>.

Constraints

• No unitary / initialize shortcuts.

Entry Point

Checks

• Exports basis_readout(bases).
• Random products of Pauli eigenstates read out as the right bits.