wave function in QM and QED

[kvblake2003@yahoo.com]

Does the wave function move in space? In QM it seems to me that it
doesnt.
But the EM wave which through the vector-potential can be thought of as
a wave function of the photon is moving with c. ????

[Jon Bell]

In article <1140594274.635598.235800@f14g2000cwb.googlegroups. com>,
<kvblake2003@yahoo.com> wrote:
>Does the wave function move in space?

It can.

>In QM it seems to me that it doesnt.

Introductory treatments of QM usually deal mainly with energy eigenstates
of bound systems. These are also called "stationary states" because their
probability distributions don't vary with time.

In bound systems, states which are superpositions of eigenstates do
generally vary with time. For example, take the classic one-dimensional
infinite square well (the "particle in a box"). Take the first two
normalized solutions psi_1(x,t) and psi_2(x,t) and form the following
combination:

psi(x,t) = [psi_1(x,t) + psi_2(x,t)]/sqrt(2)

The probability distribution psi*psi "sloshes" back and forth inside the
well as time passes.

--
Jon Bell <jtbell@presby.edu> Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA