Archive for "Marker Geometry or Slit Imbalance? A Classical Quantum-Eraser Analogue as an Undergraduate Exercise in Parameter Identifiability"

This archive supports the manuscript "Marker Geometry or Slit Imbalance? A Classical Quantum-Eraser Analogue as an Undergraduate Exercise in Parameter Identifiability" by Liam Salcedo (Seton Hall Preparatory School, West Orange, New Jersey, USA). This version, 1.4.0, carries the manuscript as revised for submission. Relative to version 1.3.0 it changes the manuscript only, in four sentences, and no measured result: Section 3.1 now describes the double slit as a double slit in a slide frame rather than a commercial slide of nominal 0.45 mm separation, the label value staying where Section 3.4 and supplementary Section S2 compare the measured 0.467 mm with it; Section 3.3 ends with a sentence stating that the code and the reanalysis were written with assistance from generative AI; and the Figure 1 caption notes that its plotting code was AI-assisted, as the captions of Figures 2 to 4 already did. The supplement, photographs, frame maps, run sheets and code are unchanged from 1.3.0. Since version 1.2.0 the manuscript gained two figures of the measurements themselves, after a reader pointed out that it showed none: Figure 2 photographs six configurations from the reference session, and a walkthrough follows one frame through every step of the analysis to the visibility it yields, which is the value that frame carries in the deposited frame map. The main text was then shortened around the laboratory exercise, with the detailed audit material moved to the supplement. The main text keeps four figures: the apparatus schematic, the six control configurations, the reference session against the equal-illumination bisector, and the two principal sessions compared. The extraction walkthrough and the slit-ratio consistency comparison are supplementary Figures S1 and S2, the full tables for the reference session and for Run 7.1 are in supplementary Sections S3 and S15, and the protocol of Section S11 is framed as an extension of the exercise. One unsupported number was removed: the bright core was described as 35 to 40 px tall, which the archived frames do not bear out, and the text now says a few tens of pixels. No measured result changes. The manuscript also carries its new title and supplementary Sections S12 to S14, and code/ gains make_fig_controls.py, make_fig_extraction.py, block_overlap.py, flux.py, null_tail2.py, pilot.py, setting_error.py and tone_curve.py, which reproduce Figures 2 and S1, Sections S12 to S14, the detector-response table of Section S8 and the photometric slit ratios of Section S3; all are wired into reproduce_all.py. A double slit with a linear polarizer over each slit marks the two paths by polarization and suppresses the fringes. A third polarizer after the slits, the analyzer, restores them. The textbook treatment places the visibility maximum at 45 degrees. This work measures where it actually falls, derives the general relation for markers that are not exactly perpendicular and slits that are not equally illuminated, and shows that a sparsely sampled analyzer sweep cannot distinguish those two causes. Scanning the analyzer through both extinction minima constrains the effective marker geometry independently, at a cost of about twenty minutes of extra bench time. The optical components and materials were bought for under 70 US dollars and the apparatus was built at home; the smartphone used as the detector was already owned. The work is a classical optical analogue, not a quantum eraser. This record holds 15 files. README.md describes the archive as a whole. The photographs are split into one zip per session, so that a reader can take a single session without downloading everything; extracting those alongside Salcedo_QE_code_data_manuscript.zip reproduces the directory tree below. photographs/ - 1158 frames in 11 directories, one per session: pilot, bare_beam_check, run1, run2, run3, run4, run5, run6, run7, run7.1 and run8. Every frame excluded from analysis is included, as are the two sessions excluded entirely. One setup photograph, run5/IMG_6519.jpeg, is withheld because it shows an identifiable person; its row is kept in the frame map with the reason recorded, so the campaign's 1159 archived frames are accounted for by the 1158 deposited here. Runs 3 through 8 account for 1040 of them, which is the number quoted in the manuscript. data/ - CSV frame maps for Runs 4 onward, assigning every measurement frame to a block, analyzer setting, exposure slot and replicate index, with a free-text reason recorded for every exclusion, together with Run3_Visibility_Results.csv, Run 3's per-frame visibility table, which serves the same purpose for that session. Setup and trial photography carrying no analyzer setting is not mapped this way; supplementary Section S1 accounts for those frames by number. code/ - the extraction, resampling and figure-generation code, with a pinned environment specification and the fixed random seed (20260905) used for every published resampling result. figures/ - Figures 1 to 4 and supplementary Figures S1 and S2 as vector PDFs. manuscript/ - the manuscript source, the compiled PDF and the supplement. run_sheets/ - the run sheet for each session from Run 4 onward, as filled in at the bench, with a README of its own noting two header fields that were not updated during the session. The archived code regenerates Table 1, the session tables of supplementary Sections S3 and S15, Figures 1 to 4 and S1 and S2, the finite-extinction tables of Section S7, the extraction-sensitivity and detector-response results of Section S8, the photometric slit ratios of Section S3, and the results of Sections S12 to S14; code/reproduce_all.py runs them in one pass. The remaining supplementary numbers are read from the deposited frame maps and run sheets by the arithmetic the supplement states. Location metadata was removed from every deposited photograph; all other EXIF fields are unmodified and the compressed image data was not re-encoded. Images and data are released under CC BY 4.0. Code is released under the MIT License and carries its own LICENSE file in code/.