[Phys-L] Re: entropy and electricity

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

> Fayngold, Moses wrote:
>
> >  Now, suppose we have a single photon whose polarization is
> > equally likely to be found in one of two distinct states,
> > namely, either along the x- or along the y-direction,
> > after we will have passed it through, say, a polarizing
> > beam-splitter.

Then, At 10:54 AM 12/16/2005, John Denker responded in this way:

> That description is ambiguous.
>
> >  Does this mean that before that the photon's entropy is
> > 1 bit?
>
> That depends on how we disambiguate the question.  There are
> two extreme cases:
>
> a) Unpolarized light has density matrix
>            [ .5    0 ]
>            [         ]
>            [  0   .5 ]
> and has an entropy density of one bit per photon.
> /snip /


Hmmmm.... Moses talks of a single photon, and John responds with
  properties of an ensemble of photons expressed as an average value
  per photon.   Is that it?



Brian Whatcott    Altus OK    Eureka!
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