The Heisenberg equation is the fundamental equation of quantum mechanics in the so-called Heisenberg formulation.
In quantum mechanics the observable physical quantities are quantified and are in the form of a hermitian operator .
A particularly important operator is the Hamiltonian operator defined from the total energy of the physical system under consideration, such as the hydrogen atom, an electron in a magnetic field etc.
The equation of motion of a physical quantity involves these operators and is written:
where and is the Planck constant divided by .
This is the Heisenberg equation.