Re: photodetector coincidence or anticoincidence ?

From: Joe Rongen (joe_at_alpha.to)
Date: 10/13/04 

Date: Wed, 13 Oct 2004 19:13:38 +0000 (UTC)

"Patrick Van Esch" <vanesch@ill.fr> wrote in message
news:c23e597b.0410122300.35380958@posting.google.com...
>
> carlip-nospam@physics.ucdavis.edu wrote in message
news:<ckh6k0$8e8$2@skeeter.ucdavis.edu>...
>
> > It has. Grangier et al. used an atomic cascade as a trigger rather than
> > a parametric down converted photon pair, but it's been redone your way;
> > see Thorne et al., Am. J. Phys. 72 (September 2004) 1210. There's a
> > reprint on the Web, along with a description of how to do the experiment
> > yourself, at
http://marcus.whitman.edu/~beckmk/QM/grangier/grangier.html.
>
>
> Thanks a lot. From September 2004 !! I'm in sync with what happens
> at the frontlines of current research in quantum optics :-))
> The paper addresses indeed exactly what I was aiming at. A pity one
> has to be subscribed (my institute is) to read it.

One can download another project for free here (1.2 Mb):

http://departments.colgate.edu/physics/research/Photon/ajpphtwf.pdf

"Photon Quantum Mechanics
This is a project funded by the National Science Foundation to establish
a set of undergraduate laboratories to study the fundamentals of quantum
mechanics. The experiments are laboratory exercises on topics of quantum
mechanics that are otherwise theoretical, abstract or even unintuitive. The
central issue of the experiments is quantum superposition: the ability of a
quantum to be in two places at the same time or to be in to be in a
correlated superposition of states with other quanta."

Regarding their detectors:

http://departments.colgate.edu/physics/research/Photon/detectors.htm

"The photon detectors need to have high efficiency because coincidence
detection depends on the product of the efficiencies on the two detectors.
Photomultipliers are not good enough because their efficiencies are low
in the near infrared. For this reason everybody uses avalanche photodiodes."

Stated under Fig. 1
"Single photon detectors in its enclosure.
We have about 300 s-1 dark counts."

Is that not a very high dark count to start with?

Regards Joe

" ...not only are the drops of rain mere appearances, but even their
round shape, and even the space in which they fall, are nothing in
themselves, but merely modifications of fundamental forms of our
sensible intuition, and the transcendental object remains unknown to
us"

Kant, I. Critique of Pure Reason. 

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