M1L5h_CQ8.txt

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The next thing is now you can't have the solution that we take
sort of a big photodiode and combine the two
beams, because I'm asking you now is, what
is the variance in i1 minus i2?
So you subtract the two carbons.
So the question is, if you're a technical noise
the two beams would be fluctuating,
and you would form i1 minus i2.
All the technical noise would cancel away.
But what is shot noise?
Is shot noise technical noise?
Is shot noise that every time you
prepare an ensemble there is a hiccup,
and you can split it and subtract it?
So now it's getting really interesting.
To what extent does a beam splitter
that's a split coherent state, which has shot noise, and you
now perform the difference of the measurement--
can you get rid of some of the shot noise or not?