Bell states {|Φ±⟩, |Ψ±⟩}: maximally-entangled 2-qubit basis

The four Bell (Einstein-Podolsky-Rosen-Bohm) states are a maximally-entangled orthonormal basis for 2-qubit Hilbert space C² ⊗ C²: |Φ^±⟩ = (|00⟩ ± |11⟩)/√2 and |Ψ^±⟩ = (|01⟩ ± |10⟩)/√2. Properties: (i) each Bell state has maximal…