# Addition of Angular Momenta in Quantum Mechanics

Requires a Wolfram Notebook System

Interact on desktop, mobile and cloud with the free Wolfram CDF Player or other Wolfram Language products.

Requires a Wolfram Notebook System

Edit on desktop, mobile and cloud with any Wolfram Language product.

Angular momentum in quantum mechanics is a quantized vector with magnitude and component in any direction, conventionally chosen as the axis. The quantum numbers are restricted to integer or half-integer values: , with . Vector addition of two angular momenta is restricted by a triangle inequality with . Although quantum formalism is indifferent to such interpretations, the addition of angular momentum in the absence of any electric or magnetic field can be pictured by a vector model in which and precess about , which itself precesses about a axis. The amplitude for addition of and to give with component can be expressed in terms of Clebsch–Gordan coefficients as with the sum restricted by . You can set the precessions into motion with the trigger control. To choose a new set of and values, pause and reset the trigger.

Contributed by: S. M. Blinder (March 2011)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

Reference: S. M. Blinder, *Introduction to Quantum Mechanics*, Amsterdam: Elsevier, 2004 pp. 85–86.

## Permanent Citation

"Addition of Angular Momenta in Quantum Mechanics"

http://demonstrations.wolfram.com/AdditionOfAngularMomentaInQuantumMechanics/

Wolfram Demonstrations Project

Published: March 7 2011