OpenQASM3 Frontend

[ACE07-Sev]

Description

Initial commit to tackle #1503

---

License

• I license this contribution under the terms of the GNU GPL, version 3 and grant Unitary Foundation the right to provide additional permissions as described in section 7 of the GNU GPL, version 3.

Before opening the PR, please ensure you have completed the following where appropriate.

• I added unit tests for new code.
• I used type hints in function signatures.
• I used Google-style docstrings for functions.
• I updated the documentation where relevant.
• Added myself / the copyright holder to the AUTHORS file

[ACE07-Sev]

In this one I believe only mitiq/pec has some failures which is exactly the same as the #2839 case (mitigated error being exactly the same as unmitigated). Besides that, openqasm3.ast.Program (the datatype for OpenQASM3's circuit afaik) has some issues with mypy.

Besides these, should be fine. Kindly have a look and let me know if there are any thoughts :) .

[natestemen]

Awesome start! A few high level comments to align on before we get into the weeds.

[ACE07-Sev]

@natestemen Greetings,

Hope you're doing well. Anything I need to do for this PR?

[b-goldsmith]

Doing a search to see where the other frontends are included in the code...

@ACE07-Sev while I see test cases added for openqasm in the existing test files, I do not see specific openqasm test cases. The other frontends in mitiq/interface/mitiq_* include a tests folder with specific use cases. We should be testing things for openqasm, like confirming expected behavior when an invalid string is provided.

mitiq/README.md includes a Supported frontends section that should be updated.

In docs/source/apidoc.md there is an Interface section that includes the other frontends.

As a reminder, we should create an issue to include an example of ZNE with OpenQASM3. Once that is completed the docs/source/guide/frontends-backends.md can be updated with a link like the other frontends.

[ACE07-Sev]

Greetings Brian,

Hope you're doing well. Thank you for the review!

@ACE07-Sev while I see test cases added for openqasm in the existing test files, I do not see specific openqasm test cases. The other frontends in mitiq/interface/mitiq_* include a tests folder with specific use cases. We should be testing things for openqasm, like confirming expected behavior when an invalid string is provided.

I'd appreciate giving me a list of items to write testers for. I can't really use other interfaces as an example since they differ significantly from one another.

The other items you mentioned seem to be the doc parts which I'll add now.

[ACE07-Sev]

@bdg221 OpenQASM doesn't have a logo apparently. What image should I use?

[natestemen]

Looking good, but a few individual unit tests demonstrating basic circuit conversions would be useful, and we need to sort out the type of object we expect from users. I think str is the most user-friendly, but I'm not sure that would work in the current state.

Thanks for your continued work here!

[natestemen]

LGTM! Just some small questions/comments.