Add and validate GraphMonomorphismMapper initial placement strategy#7827
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sefunmi4 wants to merge 9 commits intoquantumlib:mainfrom
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Add and validate GraphMonomorphismMapper initial placement strategy#7827sefunmi4 wants to merge 9 commits intoquantumlib:mainfrom
sefunmi4 wants to merge 9 commits intoquantumlib:mainfrom
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sefunmi4
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cirq-cync - @pavoljuhas to do the initial review and than ask Tanuj for further feedback. |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #7827 +/- ##
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Coverage 99.57% 99.57%
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Files 1104 1106 +2
Lines 98938 99144 +206
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+ Hits 98517 98723 +206
Misses 421 421 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Summary
This PR refines and validates the GraphMonomorphismMapper initial placement strategy for routing. The mapper embeds a circuit’s logical interaction graph as a monomorphism into the device topology, enabling swap-free execution when such an embedding exists. This provides an alternative to LineInitialMapper, particularly beneficial for small-to-medium qubit counts and sparse interaction graphs.
Motivation
LineInitialMapper is currently the primary initial placement strategy in Cirq. For circuits with non-linear but sparse connectivity, graph monomorphism–based placement can yield better initial layouts and avoid unnecessary swaps. This work supports ongoing efforts to expand Cirq’s routing strategies and aligns with discussions in issue #5859.
What changed
• Adjusted and formatted GraphMonomorphismMapper implementation for consistency with Cirq style.
• Updated and validated tests covering:
• Small circuits
• Line-like circuits
• Grid and ring device topologies
• Failure cases where no monomorphism exists
• Ensured deterministic, bounded runtime behavior in tests.
Testing
All checks were run in the Cirq development environment:
• ./check/format-incremental --apply
• ./check/pytest-changed-files -n 0
• ./check/mypy
• ./check/misc
All tests, type checks, and formatting checks pass.