Add mask for entangling gates

[eileen-kuehn]

This PR adds functionality to support removal of entangling gates from a given circuit via Masks. Idea to support this feature is to explicitly support lowering the expressivity of a quantum circuit and therefore maybe raising the trainability.

Closes #31.

[codecov]

Codecov Report

Merging #32 (6c7a37d) into main (0076739) will increase coverage by 3.46%.
The diff coverage is 98.27%.

@@            Coverage Diff             @@
##             main      #32      +/-   ##
==========================================
+ Coverage   75.13%   78.60%   +3.46%     
==========================================
  Files          15       15              
  Lines        1122     1173      +51     
  Branches      108      117       +9     
==========================================
+ Hits          843      922      +79     
+ Misses        275      246      -29     
- Partials        4        5       +1     

Impacted Files	Coverage Δ
main.py	0.00% <0.00%> (ø)
maskit/circuits.py	84.21% <100.00%> (+84.21%)	⬆️
maskit/masks.py	100.00% <100.00%> (ø)
tests/test_masks.py	100.00% <100.00%> (ø)

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[eileen-kuehn]

@maxfischer2781, when reviewing, please have a specific look on how the entangling_mask is currently handled. I opted for making it optional what requires to test if it is set in case actions are performed. This will probably fail for the execute function if the mask is not properly initialised.
Any ideas on this? Further, I am a bit afraid, that this mask might even have not a so well-defined shape... However, I would like to give it a try already. What do you think?

[maxfischer2781]

I've only sprinkled is not Nones on the cases that were relying on implicit falseyness. That's somewhat faster and should be more robust if you ever refactor.

Do you think you can hit the continues with unittests? I can't really comment on whether they work as expected.

[maxfischer2781]

Sorry, I missed your previous comment. TBH I'm not totally sure how exactly this change works, so it's hard for me to say how it might affect other things.

Perhaps we should discuss at a literal drawing board. :P

[eileen-kuehn]

Do you think you can hit the continues with unittests? I can't really comment on whether they work as expected.

I added another unit test that should exactly test for that :) Now you will have to review again!

[maxfischer2781]

Pretty sneaky just raising the coverage while I was looking... 😜