In an internal Atomic Energy Commission document published in 1952 [1], Julian Schwinger developed the quantum theory of angular momentum from the commutation relations for a pair of independent harmonic oscillators. This work has since been subsequently quoted many times [2, 3]. A simplified version of the derivation is given in the Details. This Demonstration shows the angular momentum states , derived from the quantum numbers for a pair of harmonic oscillators, with .
A pair of uncoupled harmonic oscillators, designated a and b, can be defined by raising and lowering operators with commutation relations , . It can then be shown that the operators obey the canonical commutation relations for angular momentum: The number operators for the two oscillators are given by with corresponding eigenvalues , , , each equal to an integer . In terms of the number operators, relevant angular momentum operators can be expressed as , . The quantum number evidently can be identified with , with possible values . Analogously, , running from to in integer steps. [1] J. Schwinger, "On Angular Momentum," U. S. Atomic Energy Commission Report NYO3071, January 26, 1952. www.osti.gov/biblio/4389568. [2] J. J. Sakurai, Modern Quantum Mechanics, Menlo Park, CA: Benjamin/Cummings, 1985 pp. 217–221.
