Testing methodology for the Chinese quantum satellite link?

Fri Jul 14 00:04:52 UTC 2017

On Thu, Jul 13, 2017 at 12:57 PM, Bill Woodcock <woody at pch.net> wrote:

> Does anyone who understands quantum networking better than I do have an
> opinion on the testing methodology that the Chinese team used to confirm
> entanglement?

Their paper

https://arxiv.org/abs/1707.01339

This is somewhat higher level

http://vcq.quantum.at/fileadmin/Publications/Entanglement-based%20quantum%20communication%20over%20144km.pdf

More math

https://arxiv.org/pdf/1410.1319.pdf

> I guess, more specifically, my question is: when they say that they got
> 911 positive results out of “millions” of attempts, does this significantly
> exceed any expected false-positive rate for the confirmation methodology?
> If so, by what margin?  Obviously, if you were just flipping coins, and
> measured the results once, you’d get 50% positive correlation, twice and
> you’d get 25% correlation, ten times and you’d get 0.1% correlation, and
> you’d be at 911 out of a million.  So, how much better than that are we
> talking about?
>

Look at Figure 2b in the Ursin paper. You are always doing this against
some background, looking for a statistically significant peak.

Regards
Marshall

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