Editing Quantum superposition (section)

=== General formalism ===
Any quantum state can be expanded as a sum or superposition of the eigenstates of an Hermitian operator, like the Hamiltonian, because the eigenstates form a complete basis:
:<math>
 |\alpha\rangle = \sum_n c_n |n\rangle,
</math>

where <math>|n\rangle</math> are the energy eigenstates of the Hamiltonian. For continuous variables like position eigenstates, <math>|x\rangle</math>:

:<math>
 |\alpha \rangle = \int dx' |x'\rangle \langle x'|\alpha \rangle,
</math>

where <math>\phi_\alpha(x) = \langle x| \alpha \rangle</math> is the projection of the state into the <math>|x\rangle</math> basis and is called the wave function of the particle. In both instances we notice that <math>|\alpha\rangle</math> can be expanded as a superposition of an infinite number of basis states.