Challenge B3

Generate Bell state

You are given two qubits in state |00⟩ and an integer index. Your task is to create one of the Bell states on them according to the index:

0: |B0⟩ = 1/√2 (|00⟩ + |11⟩)

1: |B1⟩ = 1/√2 (|00⟩ - |11⟩)

2: |B2⟩ = 1/√2 (|01⟩ + |10⟩)

3: |B3⟩ = 1/√2 (|01⟩ - |10⟩)

You have to implement the Solve operation to make the correct Bell state according to the given index. The operation should have the following signature: