[Interface] equivalence checker for OpenQASM files

[ScottWe]

Summary

A command-line executable for verifying OpenQASM files using verify_equvialences.py.

Purpose

The equivalence checker in Quartz is considered state-of-the-art in the quantum circuit verification community. Inevitably, people will want to use this verifier to build new tools, or to evaluate new parameterized equivalence checking techniques. However, working with verify_equivalences.py can be challenging, since it requires a specialized json input. This pull request introduces a new executable, which allows the verifier to work directly on OpenQASM files.

Details

This pull request introduces a new executable (verify_openqasm) which works as follows:

• A context is set up with support all gates that Quartz supports from stdgates.inc.
• This context is used to set up an OpenQASM 3 parser, with support for symbolic multiples of pi.
• Two OpenQSAM 3 files are taken as command-line arguments, and then parsed using the parser. The same parser is used for both files, to ensure that common symbolic parameters are correlated.
• The resulting circuit sequences are added to a dataset, to identify possible equivalences and global phase fingerprints.
• The dataset is dumped to tmp.json, for analysis by verify_equivalences.py.
• The results from verify_equivalences.py are logged to res.json.

I think this will suffice for simple use cases.

[xumingkuan]

Great, thanks! I added a commit to allow the executable to run in any directory so we don't need to worry about the relative path when calling verify_equivalence.py.