Misty Wahl

@andreamari, tests are passing and execution time is looking much better! Using - `Nelder-Mead` solver instead of `BFGS` - `num_samples = 50` instead of `num_samples = 5000` - Applied initial...

> Thanks @Misty-W! Adding non-cirq tests would make CI too slow? What about if we add a non-cirq test just for `biased_noise_loss_function`? Still too slow? > > A few other...

@andreamari, thanks for the review yesterday! Anything else to address before merging?

Merged at last! Many thanks for your guidance and feedback @andreamari and @nathanshammah! cc: @willzeng, @natestemen

Added a label in `pec.myst` for linking to the PEC section of the user guide (instead of re-explaining PEC in the text of the example).

> Thanks @Misty-W. Just to clarify, a side comment because there are a couple of PRs open: > > * [Write user guide section for learning-based PEC #1395](https://github.com/unitaryfund/mitiq/pull/1395): this PR...

Thanks for the review @natestemen! > > Some general feedback: > > * Some more explanation between cells might be helpful instead of describing what the code is doing. Agreed,...

> Thanks @Misty-W, I left some optional suggestions. Do you have any idea of how long is the execution time? Comparing with docs build time on master this seems 15-20...

> Nice work Misty! I really like this example. It's clear, and shows a nice clear advantage while using this technique. > > I've left 3 comments, all of which...

Tests are passing but running long on this two-parameter version. Propose to pre-execute PEC and store the values in a file as previously discussed, at least for learning biased noise...