CBF Prediction:
In large-N slit gratings, a finite temporal coincidence window of the Event Ledger
limits perfect phase reconciliation for very high fringe orders. Visibility decreases
with order even when geometric coherence is satisfied:
VCBF ≈ VQM · (1 − n²·τgate/Tcoh)
where n is fringe order, τgate is the Ledger’s effective timing gate,
and Tcoh is source coherence time.
Standard QM:
For path differences within the coherence length, visibility is order-independent.
No systematic n-dependent drop beyond optical imperfections.
Experimental Signature:
- High-quality transmission grating with N ≥ 1000 slits and sub-µrad angular stability.
- Measure visibility for n = 10–20 while holding geometry and illumination constant.
- CBF expects a small, systematic reduction at high orders, target scale ~10⁻⁴ relative to low orders.
- Use intensity-linear detectors and flat-field calibration to reach <0.1% visibility uncertainty.
Controls / Confounds:
- Grating MTF: Characterize grating transfer function at high spatial frequencies and deconvolve it.
- Source linewidth: Lock laser and verify Tcoh ≫ optical path spread across measured orders.
- Detector linearity: Calibrate pixel response, avoid clipping, correct for blooming/PRNU.
- Aperture vignetting: Keep pupil fixed, confirm identical NA across orders.
Falsification Threshold:
If, after deconvolving grating MTF and detector effects, high-order visibility matches
standard QM (no residual ∝ n² dependence within the error budget), the finite
coincidence-window prediction is falsified.