Certified accuracy of a Hubbard simulator where numerics fail

Choose a point $(U/t, \delta, T/t)$ where unbiased numerical methods lose control (for example $U/t = 8, \delta = 0.1, T/t < 0.1$). Using Hamiltonian learning of t, t', U and harmonic confinement, entropy thermometry, and stability bounds, give a certified error bar on the nearest-neighbour spin correlator $C(1,0)$ and on the density. Answer: an error budget with all sources listed and a total below 5%.

A published error budget combining in-situ Hamiltonian calibration with a proof or numerical bound on how parameter errors propagate to local observables.