Heisenberg picture formulation of matrix mechanics in an arbitrary basis, in which the Hamiltonian is not necessarily diagonal. It further serves to define a third, hybrid, picture, the interaction picture. In the Heisenberg picture of quantum mechanics the state vectors, |"ψ("t")"〉, do not change with time, while observables satisfy where is the Hamiltonian and <nowiki>[•,•]</nowiki> denotes the commutator of two operators (in this case and ). Taking expectation values automatically yields the Ehrenfest theorem, featured in the correspondence principle. By the Stone–von Neumann theorem, the Heisenberg picture and the Schrödinger picture are unitarily equivalent, just a basis change in Hilbert space. In
Heisenberg group a group, as is shown by the multiplication: and The Heisenberg group is a simply-connected Lie group whose Lie algebra consists of matrices where By letting e, ..., e be the canonical basis of R, and setting the associated Lie algebra can be characterized by the canonical commutation relations, where "p", ..., "p", "q", ..., "q", "z" are the algebra generators. In particular, "z" is a "central" element of the Heisenberg Lie algebra. Note that the Lie algebra of the Heisenberg group is nilpotent. The exponential map is given by the following expression The exponential map of a nilpotent Lie