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RESEARCH PRODUCT

A pedagogical approach to the Magnus expansion

J A OteoSergio BlanesJ. RosFernando Casas

subject

PhysicsProperty (philosophy)UnitarityPerturbation (Quantum dynamics)--Study and teachingGeneral Physics and AstronomyMagnus expansionQuantum mechanicsUnitary stateStudents in advanced coursesPertorbació (Dinàmica quàntica)--EnsenyamentSchrödinger equationExponential functionsymbols.namesakeSimple (abstract algebra)Exponential perturbation theoryMagnus expansionsymbolsPerturbation theoryMathematical physics

description

Time-dependent perturbation theory as a tool to compute approximate solutions of the Schrodinger equation does not preserve unitarity. Here we present, in a simple way, how the Magnus expansion (also known as exponential perturbation theory) provides such unitary approximate solutions. The purpose is to illustrate the importance and consequences of such a property. We suggest that the Magnus expansion may be introduced to students in advanced courses of quantum mechanics.

yearjournalcountryeditionlanguage
2010-07-01
10.1088/0143-0807/31/4/020http://hdl.handle.net/10261/41952