Binary atom-gap antenna coupled to a feedthrough waveguide

validated · 2026-08-28

invdesresolution 1invdescavity_qedbeta_factorwaveguidefree_formsymmetrybinaryhard_vacuum_gap

This case checks optimization performance: the best objective reached, not geometry identity or convergence speed.

Differentiable inverse-design result and convergence history.

What is exercised

Stage one is deliberately ordinary density topology optimization. It starts from a generic nearly uniform control field, maximizes the actual waveguide branching ratio, follows a fixed projection schedule, and ends with an exact binary straight-through mask. No cavity or optimized geometry is used as a warm start. Equal left/right emission is imposed by x symmetry, so a total guided beta of 0.90 means 0.45 into each physical propagation direction.

This case runs at its declared full benchmark resolution (resolution factor 1.0).

Recorded result

Metric	Observed / error	Reference / limit	Error	Effective budget	Result
guided_beta	—	—	—	—	CHECK
gap_dielectric_violation	—	—	—	—	CHECK
material_binary_fraction	—	—	—	—	CHECK

The table is rendered from progress.json; it is not a hand-written success claim. For metrics that report an error directly, the “observed” column repeats that error and the reference column is the acceptance threshold.

Reproduce

uv run fdtdx-bench run --case invdes_scratch_atom_beta

Implementation and provenance: benchmarks/cases/invdes_scratch_atom_beta/case.yaml, benchmarks/cases/invdes_scratch_atom_beta/run.py.

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