Re: Is photon a wave packet ?

["John S. Denker" <jsd@MONMOUTH.COM>]

Arnulfo Castellanos Moreno wrote:
> In my opinion, M. Edmiston give us good question.

Yes, it's a famous experiment.  The answer is well known.
The laws of physics say that defining a notion of "wave"
distinct from the notion of "particle" is a waste of time.
There are no unwavelike particles.  There are no unparticlelike
waves.

> We can count photons to get an statistical picture,
> but is this evidence of spatial distribution of them?

I hope not.

-- Photon number is one question.
-- Spatial extent of a wave packet is entirely another
question.

There are many reasons including dimensional analysis
why it is clear that these are different questions.

Consider an electromagnetic wave trapped in a shiny box.
The wave is clearly localized.  It extends from wall to
wall within the box, and no farther.  The extent may be
measured in meters.  In a box (and not in a free field)
there will be discrete modes.

The photon number is entirely a separate question.  It
has to do with the magnitude of the wave.  The magnitude
may be measured in volts per meter, or optionally (V/m)
squared, or optionally by occupation number.  The discreteness
of the occupation numbers is completely different physics
from the discreteness (if any) of the spatial mode structure.
That is, the spacing between levels within a mode has
nothing to do with what other modes the box may have.