Hamiltonian operator


Definition 0.1 The Hamiltonian operatorPlanetmathPlanetmath H introduced in quantum mechanics (QM) by Schroedinger (and thus sometimes also called the Schroedinger operator) on the Hilbert space L2(n) is given by the action:

ψ[-2+V(x)]ψ,ψL2(n),

The operator defined above [-2+V(x)] , for a potential function V(x) specified as the real-valued function V:n is called the Hamiltonian operator, , and only very rarely the Schrödinger operator.

0.1 Schroedinger formulation of QM

The energy conservation (quantum) law written with the operator as the Schrödinger equation is fundamental in quantum mechanics and is perhaps the most utilized, mathematical computation device in quantum mechanics of systems with a finite number of degrees of freedom. There is also, however, the alternative approach in the Heisenberg picture, or formulation, in which the observable and other operators are time-dependent whereas the state vectors ψ are time-independent, which reverses the time dependences betwen operators and state vectors from the more popular Schrödinger formulation. Other formulations of quantum theoriesPlanetmathPlanetmath occur in quantum field theories (QFT), such as QED (quantum electrodynamics) and QCD (quantum chromodynamics).

0.2 Heisenberg formulation of QM

Although the two formulations, or pictures, are unitarily (or mathematically) equivalentMathworldPlanetmathPlanetmathPlanetmathPlanetmath, however, sometimes the claim is made that the Heisenberg picture is “more natural and fundamental than the Schrödinger” formulation because the Lorentz invariance from General Relativity is also encountered in the Heisenberg picture, and also because there is a ‘correspondence’ between the commutator of an observable operator with the Hamiltonian operator, and the Poisson bracket formulation of classical mechanics. If the state vector ψ, or |ψ does not change with time as in the Heisenberg picture, then the ‘equation of motion’ of a (quantum) observable operator is :

ddtAquantum=(i)-1[A,H]+(At)classical
Title Hamiltonian operator
Canonical name HamiltonianOperator
Date of creation 2013-03-22 18:11:32
Last modified on 2013-03-22 18:11:32
Owner bci1 (20947)
Last modified by bci1 (20947)
Numerical id 34
Author bci1 (20947)
Entry type Definition
Classification msc 81P05
Classification msc 81Q05
Classification msc 81-00
Synonym Schrödinger operator
Synonym Schrödinger formulation of QM
Related topic QuantumSystem
Related topic HamiltonianAlgebroids
Related topic LieAlgebroids
Related topic MathematicalBiology
Related topic Quantization
Related topic SchrodingersWaveEquation
Related topic SchrodingerOperator
Related topic CanonicalQuantization
Related topic QuantumSpaceTimes
Defines QM
Defines energy conservation in finite quantum systems
Defines Heisenberg formulation of QM