Quantum Physics, Physics, Science, Innovation, Mathematics.
It’s the state that will be transformed by the action of the beam splitter. 1/sqrt(2)​: The use of a this​ factor suggests that the beam splitter is of the 50/50 type, where the input state ∣ψi​⟩ is split into a superposition of two paths with equal probability amplitudes. ∣1⟩ and ∣2⟩: These