Operators with a common set of eigenvectors commute

Metadata
aliases: []
shorthands: {}
created: 2022-01-06 02:14:55
modified: 2022-01-10 04:13:04

Let a complete set of eigenvectors , of operators and be given, with eigenvalues and respectively. Then and commute:

Where is the commutator.

Proof

From

Follows that from an arbitrary vector

Using the commutator yields zero as well since it is linear:

So the commutator yields for any vector, which means that it is the zero operator:

QED

See also