Add Dynamic QFT benchmark

[gshaowei6]

Description

Adds a dynamic_qft benchmark implementing the semiclassical Dynamic QFT with mid-circuit measurements and classically controlled phase rotations. The implementation follows the current benchmark registry pattern, uses the canonical Dynamic QFT naming, keeps the classical register named c, and rejects instances above 64 qubits to avoid impractically small phase shifts.

Fixes #798

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
• I have added entries to the changelog for any noteworthy additions, changes, fixes, or removals.
• I have added migration instructions to the upgrade guide (if needed).
• The changes follow the project's style guidelines and introduce no new warnings.
• The changes are fully tested and pass the CI checks.
• I have reviewed my own code changes.

If PR contains AI-assisted content:

• I have disclosed the use of AI tools in the PR description as per the AI Usage Guidelines.
• AI-assisted commits include an Assisted-by: GPT-5 via Codex footer.
• I confirm that I have personally reviewed and understood all AI-assisted content, and accept full responsibility for it.

Verification

• python -m pytest tests\\test_bench.py -q -k dynamic_qft -p no:benchmark -n0 --basetemp .tmp-pytest -> 4 passed
• python -m pytest tests\\test_bench.py -q -p no:benchmark -n0 --basetemp .tmp-pytest -> 199 passed
• python -m pytest -q -p no:benchmark -n0 --basetemp .tmp-pytest -> 243 passed
• WSL Ubuntu: python -m pytest -q -p no:benchmark -n0 --basetemp .tmp-pytest-wsl -> 243 passed
• python -m ruff check src\\mqt\\bench\\benchmarks\\dynamic_qft.py tests\\test_bench.py
• python -m ruff format --check src\\mqt\\bench\\benchmarks\\dynamic_qft.py tests\\test_bench.py
• PYTHONPATH=<user-site> python -m ty check -> All checks passed
• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[flowerthrower]

Dear @gshaowei6, your contribution already looks good. I left only two minor comments to be addressed. Thanks for your efforts.

[flowerthrower]

Align the classical output convention with the existing qft benchmark. The measured outcomes should be written to the classical bits in the reversed order.

[gshaowei6]

Changed measurements to write q[i] into c[num_qubits - i - 1] and kept each conditional phase controlled by that same measured classical bit. Added a structure assertion for the reversed measurement mapping.

[flowerthrower]

There is still a small misalignment between the regular qft benchmark and your version. I encourage you to (visually) inspect and compare the following two circuits. Both circuits should have a matching operation order on same qubit and measurement indices.

from mqt.bench import get_benchmark, BenchmarkLevel

# original qft benchmark
circ = get_benchmark("qft", BenchmarkLevel.ALG, circuit_size=3)
circ.draw("mpl", fold=-1)

# your solution
circ = get_benchmark("dynamic_qft", BenchmarkLevel.ALG, circuit_size=3)
circ.decompose().draw("mpl", fold=-1)

[burgholzer]

Suggested change

	- Add Dynamic QFT benchmark ([#918]) ([**@gshaowei6**])
	- ✨ Add Dynamic QFT benchmark ([#918]) ([**@gshaowei6**])

To align with the rest of the changelog style.

[gshaowei6]

Applied the suggested changelog entry style with the ✨ prefix.

[gshaowei6]

Addressed the three review comments in b8d3ff1:

• Removed the Dynamic QFT qubit cap and added 65-qubit coverage.
• Reversed the classical measurement mapping while keeping feed-forward conditions tied to the measured bit.
• Applied the changelog entry style.

Local verification:

• \python -m ruff check src\mqt\bench\benchmarks\dynamic_qft.py tests\test_bench.py\
• \python -m ruff format --check src\mqt\bench\benchmarks\dynamic_qft.py tests\test_bench.py\
• \python -m pytest -n0 -p no:benchmark\ -> 243 passed