Bell state

noun1

1. •
   One of a set of four entangled states, namely |Φ⁺⟩=1/√(|00⟩+|11⟩), |Φ⁻⟩=1/√(|00⟩-|11⟩), |Ψ⁺⟩=1/√(|01⟩+|10⟩), and |Ψ⁻⟩=1/√(|01⟩-|10⟩), where |xy⟩:=|x⟩⊗|y⟩; these are the simplest examples of entangled states.