Supplementary data and code for "Fixed-axis access to retained qubit information near Floquet quasienergy crossings"

Supplementary data and code accompanying the manuscript “Fixed-axis access to retained qubit information near Floquet quasienergy crossings” by Matthias Jakob. The archive contains hierarchical equations of motion (HEOM) benchmark data and analysis scripts, together with second-order time-convolutionless (TCL2) plotting code and input data. These materials support the comparison of classical and quantum Fisher information and the assessment of information accessible through a fixed measurement axis. This release extends the corrected Floquet-TCL2 reproducibility package v0.5.0 (DOI: 10.5281/zenodo.22859650) for the revised manuscript “Quasienergy protection does not imply readability: Detector-relative access to memory in a periodically driven open qubit” (manuscript v0.15). It combines the published full-coefficient spin-boson calculations with new laboratory-frame detector controls (A2) and an optimized fixed-laboratory-axis study (A3).At the fifth quasienergy crossing, the projective readout curvature of the drive-tracked Floquet-y instrument is about 149.204 per copy, whereas freezing the full physical laboratory-axis trajectory gives about 2.193. The contributions from state response, instrument tracking, and their interference have signed values. The much smaller linear slope used to locate a finite-floor readout minimum is not sufficiently stable under time-grid refinement; the revised manuscript therefore does not claim precise readout-minimum offsets or ratios to the BLP backflow-peak offsets. At the same crossing and fixed preparation, one optimized Pauli axis held constant in the laboratory over measurement times attains about 90.8048% of the time-averaged quantum Fisher information; an algebraic matrix bound limits the optimum within this detector class to at most 90.8293% on the sampled TCL2 trajectories.The archive contains the unmodified v0.5.0 baseline ZIP, complete A2/A3 code and data in a checksum-preserved nested provenance chain, the revised v0.15 manuscript PDF and LaTeX source, methods reports, and a standalone integrity validator. A2/A3 address the specified fifth crossing and do not repeat the earlier 225-point parameter study. The quantitative claims remain conditional on the tested Floquet-TCL2 approximation; no nonperturbative system-bath error bound is provided. Historical nested archives retain an earlier manuscript copy solely for provenance; the top-level v0.15 manuscript is the current version.