QulacsBackend

[BrunoLiegiBastonLiegi]

This adds qulacs as an optional backend.

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.85%. Comparing base (a61f9f7) to head (bb7417b).

❗ Current head bb7417b differs from pull request most recent head 791e11a

Please upload reports for the commit 791e11a to get more accurate results.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1272      +/-   ##
==========================================
+ Coverage   99.82%   99.85%   +0.03%     
==========================================
  Files          72       74       +2     
  Lines       10560    10673     +113     
==========================================
+ Hits        10541    10658     +117     
+ Misses         19       15       -4     

Flag	Coverage Δ
unittests	99.85% <100.00%> (+0.03%)	⬆️

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[BrunoLiegiBastonLiegi]

@scarrazza some preliminary results for the qulacs backend, it looks indeed comparable with our `qibojit

1 core

8 cores

[scarrazza]

Thanks @BrunoLiegiBastonLiegi, could you please include some GPU curves too?

[BrunoLiegiBastonLiegi]

Yes I am trying to install the qulacs-gpu package on the cluster, but it requires a little bit of machinery. The pip install qulacs-gpu doesn't work, thus I am not sure how we could set that as an optional dependency.

[scarrazza]

Looks good, however we are missing documentation.

[BrunoLiegiBastonLiegi]

I added a small paragraph in the documentation about qulacs, there is not much to say as at this level we are supporting the basic features of qulacs only. What still needs to updated is the scheme in the getting started section that summarizes all the available backends. @MatteoRobbiati can I ask you hand with that?

[MatteoRobbiati]

I just opened a PR in the Xmind-diagrams repo adding Qulacs to diagrams.

[BrunoLiegiBastonLiegi]

Apparently there is some problem with qulacs and python3.12, even though it should be supporting python > 3.7 from what stated in the readme.

Edit: I was able to reproduce the problem locally, it looks like with python3.12 simply giving pip install qulacs doesn't work, as it fails to collect and install cmake and boost for some reason I presume. Manually installing them fixes the problem. qulacs/qulacs#645