# CH74 Questions

1. Feb 13, 2013

### gespex

Hello all,

I'm looking into the single-channel Bell tests, and I'm looking into Clauser and Horne's 1974 bell test.

Apparently they deal with the following inequality:
$$S \leq 0$$

For
$$S = {{N(a, b) + N(a', b') - N(a', b) - N(a, b') - N(a', \infty) - N(\infty, b)} \over N(\infty, \infty)}$$

Obviously the inequality must have been violated, but I can't find a source for the actual experiment itself. What outcome does QM predict for S, what values have been tested and what was the outcome?

Regarding the values of S QM predicts, I assume it would be:
$$N(a, b) = cos^2(b - a)$$

But what does QM predict for $N(a', \infty)$, $N(\infty, b)$ and $N(\infty, \infty)$?

So this CH74 proofs Bell's theorem better than CHSH: whereas CHSH suffers from the 'fair sampling loophole', CH74 only suffers the 'no enhancement loophole', right? I do wonder though - why assume that QM isn't true because of this loophole? It wouldn't seem too hard to build a set of rules that matches at least the same correlations of measured entangled particles, so why the assumption that something like that the 'no enhancement loophole' doesn't happen?