NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/physics/23608

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From: [e-mail]
Newsgroups: sci.physics,alt.sci.physics.new-theories
Subject: Re: QM Connection Communication Expt. re-visited.
Message-ID: <[e-mail]>
Date: 27 Jan 93 13:25:46 GMT
References: <[e-mail]>
Organization: Penn State University
Lines: 158


In article <[e-mail]>, [e-mail] (Jack Sarfatti)
says:
>
>Quantum Connection Communication
>I have been taking a fresh look at my gedankenexperiment to achieve quantum
>connection communication by disentangling an entangled state. The three
>mathematical considerations are linearity, orthogonality and unitarity. I
                                 *********  *************     *********
>think that some of the initial objections by Gallis and others regarding
>the nonlinearity of my scheme while apparently correct formally were
>actually not ocrrect physically.

You forgot one of the most important, which is LOCALITY!!!!!
The mechanisms Sarfatti described in the past have implicityly been of a type
which are either nonunitary or nonlocal (and perhaps both, since the dynamics
of the system were never specified for general initial condidtions).

My favorite general no communications proof is
"A General Argument against Superluminal Transmission through the Quantum
Mechanical Measurement Process"
by G.C. Ghirardi, A. Rimini and T. Weber
Lett. Nuovo Cimento V27 p293 (1980)

There has been a more recent follow up article, but I do not have that
reference handy.

This article shows that linear, local and probability conserving evolution
cannot permit FTL communication. (Note that nonunitary evolution _is_
also accounted for in this proof.)  The mathematical formalism of
density operators and dynamical semigroups is used, so that the proof is
more general than the usual state vector approaches.  This allows for
dissipation effects and other nasties to be accounted for in a rather
general manner.

I suggest that you read this article and endeavor to understand it before
persisting with unending variations of this nonsense.


>Here is the basic point regarding the linearity objection. In Fig.1,
>imagine two Stern-Gerlach magnets. One splits the beam, the other
>reconstructs the initial state.
>
>               _________________ |+>__________________
>  |i>         /                                       \              |i>
>------------/                                           \_______________
>            \                                           /
>              \_________________ |->__________________/
>
>Fig.1
>
>|i> = |+><+|i> + |-><-|i>
>
><+|-> = 0
>
>               ___________________ |+>______________
>  |i>         /                                     \                |f>
>------------/                                         \_________________
>            \            __                           /
>              \____|->__|U |______ e^i@|+> = U|->____/
>                        |__|
>
>Fig.2
>
>In Fig.2, a spin-flip coil U is put in only one path. The second Stern-
>Gerlach magnet is modified in design so that the two sub-beams are
>recombined to one beam. This should be possible. I think a similar
>experiment has actually been done with neutrons and neutron
>interferometers. The output state |f> is no longer the same as the initial
>state |i>. Assuming that the spin-flip does not correlate to orthogonal
>number states of the radiation oscillator but, rather, to non-orthogonal
>coherent Glauber states, we can write
>
>|f> = |+><+|i> + U|-><-|i>
>
>    = |+><+|i> + e^i@|+><-|i>
>
>    = |+>[<+|i> + e^i@<-|i>]
>
><i|i> = <f|f> = 1  implies
>
><+|i><i|->e^-i@ + <-|i><i|+>e^i@ = 0
>
>This is obviously physically correct, yet it "formally" appears to violate
>linearity in that Gallis and others apparently insist upon wanting to write
>that
>
>|f>' = U|i> = U|+><+|i> + U|-><-|i> = e^i@(+)|-><+|i> + e^i@(-)|+><-|i>
>
>which seems obviously physically wrong to me.

Sarfatti has demonstrated in past posts a gross misunderstanding of
quantum mechanics, Feynman path integrals and elementary linear algebra.
Do not take his intuition too seriously (at least not without some
formal training...)

The math is nonsense not because the math is wrong, but because the
physics is wrong.  The apparatus contains a segment which looks like
///
>
>               ___________________ |+>____________
>  |i>         /
>------------/
>            \            __
>              \____|->__|U |______ e^i@|+> = U|->
>                        |__|
>
 from your Fig.2

From the standpoint of optics, this makes sense, essentially there
are two componments, a beam splitter ( a birefringent crystal, prhaps)
and a component which rotates the polarization (a quarter wave plate?).

HOWEVER,
  there is also the part which looks like
>                                   |+>______________
>                                                    \                |f>
>                                                      \_________________
>                                                      /
>                                   e^i@|+> = U|->____/
>
>
  also from your Fig.2

This element is the bogus physics.  In order for it to work, one must be able
to get two photons of identical polarization coming in from different
directions with the same polarization, but perhaps with a phase difference
to emerge from the device in the same direction.   Classically, this
device must take two beams of light with identical polarizations,
and which vary by a phase, which are coming from two different directions
and deflect one or the other or both so that they emerge in exactly the same
directions.   In order for this to happen one needs to come up with a material
which has an index of refraction which depends upon this phase, and this just
doesn't exist.

Now, Sarfatti could just bury this issue in smoke by using non-orthogonal
states in the discussion. It's the type of thing which has happened before
and will probably happen again (the obfuscation in irrelevant detail, not
necessarily the particular technique).  It would go a long way towards
legitimizing his arguments if he would design (with specific real components,
cost is no object) an apparatus which could  presumably do what
he claims (items such as this beam recombiner would be the most crucial).
No Fantasy Apparatus allowed.

In previous posts, mathematical arguments have been used to argue
(to prove) that Sarfatti's description was unphysical.  This is one
 of the strong points of mathematical formalism.  I do not believe
that anyone had pinpointed Sarfatti's actual point of departure
(from real physics/real life) using formalism alone.  This may be a weak
side of "mere formalism".  However, what remains is that the
formalism works, but the device will/can not.

-- mike gallis
-the apparant villain of Sarffati's post.
-With three tests to write, and a stack of labs to the ceiling to grade,
why, oh why  am I wasting my time on this bullpucky AGAIN?!
-sorry dale, i don't know how to run the #@*%! spell checker either,
nor the thesaurus nor the grammer checker.:)