Add note on samping overhead to cutting tutorials

[caleb-johnson]

Resolves #225

[github-actions]

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[garrison]

The sampling overhead is the required number of samples needed to get an expectation value of a target observable within some error, $\epsilon$.

How about:

The sampling overhead is the factor by which the number of samples must increase for the quasiprobability decomposition to result in the same amount of error as one would get by sampling the original circuit.

[caleb-johnson]

How about:

Hmm your comment doesnt say Outdated, but I made this change

EDIT: I see it was just a manual quote :)

[garrison]

Thanks, this looks good. One final thought: I think the word "roughly" may be unnecessary, especially since it is followed by big-O, which is really about asymptotic behavior. I did not even notice this the first five times I read it, so it is a pretty minor point.

[caleb-johnson]

Thanks, this looks good. One final thought: I think the word "roughly" may be unnecessary, especially since it is followed by big-O, which is really about asymptotic behavior. I did not even notice this the first five times I read it, so it is a pretty minor point.

I took this from the paper and wondered why it was rough. Is it because different gates have different base terms, or is it because there is something inexact going on with the chosen epsilon? I'm going to remove it since I'm not certain either