AQC-Tensor tutorial plots should not use absolute value

[kevinsung]

URL to the relevant tutorial

https://quantum.cloud.ibm.com/docs/en/tutorials/approximate-quantum-compilation-for-time-evolution

Select all that apply

• [ ] new content request
• [ ] typo
• [ ] code bug
• [ ] out-of-date content
• [ ] broken link
• [x] other

Describe the fix or the content request.

In the first section, we get these results:

Exact:         	-0.5252
AQC:           	-0.4903, |∆| = 0.0349
AQC Comparison:	0.5424, |∆| = 1.0676

Firstly, we should investigate why the AQC Comparison is so far off. Secondly, the plot should not take the absolute value of the expected value, because that doesn't give an indication of performance. If anything, we should plot either the expected value itself, or the absolute value of the error.

For new content requests - if the request is accepted, do you want to write the content?

I will write (or already have written) a draft of the proposed content

[jlapeyre]

Here is a link to the numbers in question, in Part I, step 4 The same treatment of the data is repeated in Part II, step 4

I agree. Or, if there is some (good) reason to compare the absolute value, it should be stated. As it is, the learner can only assume there is no good reason.

I'm also not convinced of the need for the plots, ~especially given how big they are~ given that the first one only compares two floating point numbers.

After spending some time with this notebook, I think it would be easier to debug if the narrative were edited and improved.