Merminthread
Re: correlations growing exponentially with n
Date: Wed, 27 Apr 1994 00:04:29 -0700 (PDT)
From: Rhett Savage
To: David Mermin
Subject: correlations
dear david mermin,
i have written to you once before; as i am to give a little talk on the
subject in just a few hours, i'll more or less repeat the same question:
what is the qualitative meaning of the correlations in n-particle systems
which exceed the local parameter limit by an amount growing exponentially
with n?
does it link up with any other information-theoretic properties of the
n-particle systems?
respectfully,
rhett
> Date: Wed, 27 Apr 94 08:23:11 EDT
> From: "N. David Mermin"
> Subject: Re: correlations
>
> I'm not sure I can help with your question. The significance of a
> bunch of distributions violating a Bell inequality is simply that there
> exists no joint distribution in all the variables that is consistent
> (in the sense of returning those distributions as marginals) with all
> the given ones. From that point of view the only important thing is
> whether or not the inequality is violated, not the amount by which its
> violated. On the other hand people have been interested in how big
> a violation you can get (probably because the bigger the violation, the
> easier it is to detect in an experiment). I was quite surprised to
> discover that you could make the violations as big as you like by
> going to many particle states. But (as I point out in the article) it
> doesn't help you much in an experiment, since the number of detectors
> you need to function accurately also goes up when you have n particles.
>
> Hope that helps.
Date: Wed, 27 Apr 1994 08:06:31 -0700 (PDT)
From: Rhett Savage
To: "N. David Mermin"
Subject: Re: correlations
David Mermin,
Thank you very much for your prompt and succinct reply - it helped a lot.
I suppose that my question already makes clear my hunch about this matter,
which is that in some sense these correlations you are talking about are
related to interesting qualitative phenomena.
As you point out in both your article and your email, this is not so if
one's concern is to measure the degree of violation or correlation using
arrays of external detectors...
I would guess that other conditions of observation (eg. within the system
instead of without - or simply where one is interested in the whole behavior
of the system) may reveal a greater qualitative significance to these types
of correlations.
Anyway, i appreciate the reply and i will reponder these things!
Rhett
