# The uncertainity principle

1. Jul 7, 2014

### bs vasanth

When it actually 'equal to' in uncertainty principle?
For example under what conditions:
ΔxΔt = h/4$pi$

2. Jul 7, 2014

### atyy

The Gaussian is an example of a wave function in which the equality is satisfied.

A more general class are called "coherent states".
http://www.indiana.edu/~ssiweb/C561/PDFfiles/Uncertainty2008.pdf
http://www.fysik.su.se/~hansson/KFT2/extra notes/cstates copy.pdf

From the first of the above two links:
"In summary, we have seen that the coherent states are minimal uncertainty wavepackets which remains minimal under time evolution. Furthermore, the time dependant expectation values of x and p saties the classical equations of motion. From this point of view, the coherent states are very natural for studying the classical limit of quantum mechanics."

Last edited: Jul 7, 2014
3. Jul 7, 2014