Sue... wrote:

Timothy Golden BandTechnology.com wrote:
[...]

Is this what you are refering to:
"Electronic spin precession and interferometry from
spin-orbital entanglement in a double quantum dot"
http://arxiv.org/abs/cond-mat/0512324

I'll need a few minutes to digest it. ROFL

[...]

Look at Figure 5.

<<Eventually the charge limit falls to a level such that the
fully illuminated photocathode cannot deliver the
desired beam intensity. At this point the QE of the
photocathode must be refreshed. This is accomplished by
a brief deposition of additional cesium on the surface of
the photocathode. This recesiation is performed by SLC
operators with computer control, and interrupts the
beam a total of 20 min. There is a gradual decrease in
photocathode performance with each recesiation, and
after many (10=D030) recesiations the photocathode must be
heat cleaned and reactivated. >>
http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-6606.pdf

Somewhat like the thorium oxide in conventional electron valves
that gets *tired*. Not exactly the same mechanism, of course.
http://en.wikipedia.org/wiki/Hot_cathode

If this is a characteristic curve then 100% polarization implies 0%
intensity.

I don't see how you get that. The particles don't have to
be polarized to form an intense beam... AFAIK.
-

It's not even a line. It drops down hard as they try to
raise the percentage. This figure I believe to be an up/down binary
type of dichotomy, so 80% up and 20% down is about the best that can =

achieved currently.

I think you are misinterpreting the graph but that is from
a very quick read.

Now please look at

http://www.upscale.utoronto.ca/GeneralInterest/Harrison/SternGerlach/=

OK...At SLAC we saw free electrons. At 'upscale' we see
electrons but don't we know they are really bound to silver atoms???

Did I overlook the free-electron version of this experiment ???

<< Figure 12. The silver atoms pass through the inhomogeneous
magnetic field. If the beam is spatially quantized, as Sommerfeld
predicted, two spots should be observed on the screen. >>
"Appendix 5: Right Experiment, Wrong Theory: The Stern-Gerlach
Experiment"
http://plato.stanford.edu/entries/physics-experiment/app5.html

Thanks. I studied SG awhile back and never found this link. That is one
of the best reviews of Stern-Gerlach I have read. The best was a small
paperback book on experimental physics that was quite old. I forget the
author.

I do have difficulties with the SG experiment, particularly the need to
go to an elongated slit instead of a round hole. They had no intensity
so had to boost it. I have found one site where they claim to be doing
it with a pinhole and potassium atoms. Anyhow, passing things through
apertures is tricky business and clean assumptions can go wrong, and
still the actuality of doing this on the raw electron is not
demonstrated. 80% is hardly better than 75%. At 75% we could say that
there is 25% of the opposing type cancelling 25% of the desired type,
leaving a figure of 50%. If this is the theoretical peak then they've
got a blaring mathematical signal. And on the graph of this published
article 75% is the peak. Spin becomes a dichotomy rather than a
discrete quantum effect.

At the bottom they present a concept of spin filters using
nonhomogeneous magnetic field like Stern-Gerlach. These devices are a
fairy tale. If they existed they would simply plug one into these
electron guns and voila, 100% polarization.

Hmmm.... I don't know what they drink at Stanford but I am
about ready to give it a try. We expect a plethora of contradictory
pages on the web but is it pure coincidence so many are
served from Stanford? Just and aside.

It looks to me like this binary nature of the electron is not so
binary. Yet all of these people go along with this interpretation like
its perfect while their apparatus is telling them something completely
different. Doesn't this all have a bad odor about it? A large output
current at 80% is 60 microamps. That's a tiny current.

I wish you would set me straight on this.

I am not sure anyone can set either of us straight.
EPR, misinterpretation of polariser function, spin-orbit coupling,
the imaginary mag-fairies of QM
etc, etc have made this a real minefield.

I am of the opinion that most of the EPR Aspect Zeilinger type
experiments are mainly between someone's ears. QM dispenses
with some important classical effect. They don't become
new couplings just because they creep back into a
misinterpreted experiment.

The bad stuff on and off the web, vastly outnumbers the good
so I try to build a mental model around only work that's been
the subject of exhaustive and *competant* peer review.

Well here is quite a statement on that:

" Advances over the years in GaAs type polarized electron sources,
especially the progress toward higher polarization while maintaining
sufficient beam intensity, can be attributed in large part to the
demanding requirements on polarized electron sources for accelerator
applications."
[ from http://nvl.nist.gov/pub/nistpubs/sp958-lide/203-208.pdf ]

So here is perhaps what we might call a government scientist position;
a heavily funded and protective class. This is the only sentence that I
could find addressing this issue, and even here the object of the
sentence obscures the admission of the problem. When we talk about
credible sources some will sway here. This is the cream of the crop
right?

Or is it the crack of the *****? I don't look up to Uncle Sam, but
he sure is a powerful guy. Look out where he wants to put that bat that
he spends most of his time with:

The crooks in the capitol
The cooks with the capital
The cocks with crap in their eyes

I wasn't planning on getting all political here but it is a match.
Openness is not a part of the scheme. Especially when it is mission
critical Truth is exchanged for longevity.

The experimental physicists have the upper hand. I trust that the
experiments expose interesting behaviors of reality.
When experiments refute the theory that they are objects of and all
gaze on with engaged interest I start to wonder about humanity.
When a republican governmernt spends half of its revenue on tools to
destoy life we see a flaw. It is an embarrasment to be a member of such
a group.
The relevance is really in the graphic portrayal that self preservation
overrides truth and improvement. This is the human factor that we all
are susceptible to.
Fallibility has to be an accepted outcome not for some purely
mathematical reason but because we are humans doing the math.

I've had a brief look at the other links. Thanks. Keep reeling in the
skepticism. Somewhere out there is the Big Kahuna.

-Tim

For example:
"Single-electron interference at Hitachi"
Click at sidebar
http://physicsweb.org/articles/world/15/9/1/1

99.9% is just the same kind of popular-press sensationalism
that fueled all the misinterpretations of Einstein's theories.
(He may have thrown a little fuel on that fire himself but
I'll leave that for sleuths like Pentcho to chase down. ;-)

Something like this is surely worth a second look:
<<We have demonstrated single-shot read-out of single- and
two-electron spin states in a quantum dot. The spin is converted
to charge, by allowing an electron to escape from the dot or not
depending on the spin state. The charge state of the dot is then
measured using a quantum point contact next to the dot, so we
also know what the spin state was. >>
http://qt.tn.tudelft.nl/research/spinqubits/

...but I'll have a sharp eye peeled for an overlooked spin-orbit
coupling when I read it. (I haven't yet)
=20
Sue...
=20

=20
-Tim

Timothy Golden BandTechnology.com wrote:

Since you insist I'll have to go with no.

Oh.

Well, I'm not sure where to go from there.