Fisher Information as the Squared Lorentz Factor: Conformal Equivalence of the Bures and Beltrami–Klein Metrics on the Qubit Bloch Ball
The origin of the program. Three results: the tensor-level conformal identity ds²BK = 4γ²(r) ds²Bures on the open qubit Bloch ball; the closed form I(V) = 1/(1−V²) = γ²(V) for the visibility of a binary quantum measurement; and a sharp boundary — for every N ≥ 3 the Weyl tensor obstructs conformal equivalence to any constant-curvature model. One falsifiable prediction: a purity-dependent Thomas–Wigner rotation under sequential non-collinear weak measurements.
Quantum Rep. 2026, 8(3), 68 · doi: 10.3390/quantum8030068



















