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

[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 and is one of the basic structures of matrix mechanics.

See also

Table of contents (217 articles)

Index

Full contents

References

  • Griffiths, David J. (2004). Introduction to Quantum Mechanics (2nd ed.). Prentice Hall. ISBN 0-13-805326-X. 
  • Liboff, Richard L. (2003). Introductory Quantum Mechanics (4th ed.). Addison-Wesley. ISBN 0-8053-8714-5. 
  • McMahon, David (2008). Quantum Field Theory. McGraw Hill. ISBN 978-0-07-154382-8. 


Author: Harold Foppele