2026/03/31 by T. Koide, A. van de Venn
Physics and Astronomy · #quant-ph #cond-mat.stat-mech #hep-th #nucl-th
25 pages, 6 figures. Title changed, references and discussions added. Accepted for publication in Phys. Lett. A
arxiv created 2026/08/05 · arxiv updated 2026/08/06
We derive an exact information-geometric inequality valid for both Markovian and non-Markovian mixed-state dynamics. This inequality saturates into a strict equality for single qubits because they belong to the quantum exponential family. This identity enables a non-iterative linear regression approach to continuous-time quantum process tomography, which, provided the full-rank condition is satisfied, yields a unique global solution and avoids local minima traps typical of standard non-linear optimization. Furthermore, as the formulation is inherently unconstrained, negative dissipation rates provide direct evidence of non-Markovianity. Numerical simulations of the unital diagonal Bloch generator derived from the Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) master equation demonstrate the validity of this geometric estimator and highlight the necessity of error mitigation near the pure-state boundary where the inverse metric becomes singular.