qLDPCOrg / qLDPCOrg/qLDPC

Support the use of `pymatching-correlated`

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Dominant language
Python
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255
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38
Avg merge
11h 19m
Merged PRs (30d)
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Description

We currently need to either decompose or ignore non-graphlike errors to decode with MWPM. As pointed out by @HaoTy, however, pymatching supports correlated decoding of Y errors. We should be able to call the correlated decoder as well.

A note on implementation: pymatching only supports correlated decoding for an observable decoder constructed from a DEM, whereas qldpc currently always calls pymatching.Matching.from_check_matrix. So decoders.SinterDecoder needs to intercept the with_MWPM=True argument to call pymatching.Matching.from_detector_error_model (with enable_correlations=True).

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Research direction

Start with decoders.SinterDecoder and trace how with_MWPM=True currently constructs pymatching.Matching.from_check_matrix. Review the detector-error-model path and the enable_correlations=True option in pymatching. Done means MWPM decoding can use correlated decoding for Y errors through Matching.from_detector_error_model.

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Assessment

Tech stack
python
Domain
backend
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Clearly specified
Newbie friendliness
68/100

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