Physics:Quantum Commutator

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In quantum mechanics, a commutator measures how much two operators fail to commute. For two operators A and B, the commutator is[1]

[A,B]=ABBA.

A commutator compares doing two quantum operations in different orders.

Role in quantum mechanics

Commutators are central because quantum observables are represented by operators. If two observables have a nonzero commutator, the corresponding quantities generally cannot both have sharply defined values in the same state.

The canonical position and momentum commutator is

[x,p]=iI.

This relation underlies the uncertainty principle[2] and is one of the basic structures of matrix mechanics.

See also

Table of contents (217 articles)

Index

Full contents

References

  1. Griffiths, David J. (2004). Introduction to Quantum Mechanics (2nd ed.). Prentice Hall. ISBN 0-13-805326-X. 
  2. Liboff, Richard L. (2003). Introductory Quantum Mechanics (4th ed.). Addison-Wesley. ISBN 0-8053-8714-5. 


Author: Harold Foppele