The quantum harmonic oscillator is the quantum-mechanical analog of the classical harmonic oscillator. Because an arbitrary potential can usually be approximated as a harmonic potential at the vicinity of a stable equilibrium point, it is one of the most important model systems in quantum mechanics. Furthermore, it is one of the few quantum-mechanical systems for which an exact, analytical solution is known.
The Hamiltonian of the particle is:
where m is the particle's mass, k is the force constant, is the angular frequency of the oscillator, is the position operator (given by x), and is the momentum operator, (given by ) The first term in the Hamiltonian represents the kinetic energy of the particle, and the second term represents its potential energy.