# Construction Data for arXiv:2604.20838

This directory contains public homepage data for:

K. Okada and K. Kasai, "High-Girth Regular Quantum LDPC Codes from Affine-Coset Structures," arXiv:2604.20838, 2026.

Files:

- `p32_lift_summary.json`: machine-readable summary of the affine-coset `(3,8)` CSS base and the P=32 CPM lift reported in the paper.
- `p32_lift_coefficients.html`: full table of the 3072 CPM lift coefficients for the `[[16384,4142,<=40]]` code.
- `p32_lift_coefficients.csv`: CSV version of the normalized lift coefficients, with columns `side,base_row,base_col,shift_mod_32`.
- `p32_lift_coefficients.json`: JSON version of the normalized lift coefficients with metadata and the indexing convention.
- `cpm_labels.csv`: original edge-label CSV from the public decoder repository.
- `cpm_HX.mtx`: P=32 lifted `H_X` matrix in MatrixMarket coordinate format.
- `cpm_HZ.mtx`: P=32 lifted `H_Z` matrix in MatrixMarket coordinate format.
- `summary.txt`: original short lift summary from the public decoder repository.
- `FER_P32_depolarizing.pdf`: FER figure from the arXiv source.

The detailed finite-length instance is the P=32 CPM lift of the affine-coset `(3,8)` base:

- base: `[[512,174,8]]`
- lifted code: `[[16384,4142,<=40]]`
- row weight: 8
- column weight: 3
- rank(HX) = rank(HZ) = 6121
- observed decoder-derived distance upper bound: `d<=40`
- BP with post-processing at depolarizing probability `p=0.085`: 23 final failures in 2,310,469,200 trials

Lift coefficient convention:

For a base edge `(base_row, base_col)` on side `HX` or `HZ` with coefficient `s=shift_mod_32`,
the lifted row `base_row*32 + r` has a nonzero entry in column
`base_col*32 + ((r+s) mod 32)`, for `r=0,...,31`.