- Accepted Paper
Information content of Krylov observables: A machine learning approach
Phys. Rev. D - Accepted 8 October, 2026
DOI: https://doi.org/10.1103/hqts-lp2n
Phys. Rev. D - Accepted 8 October, 2026
DOI: https://doi.org/10.1103/hqts-lp2n
We employ machine learning techniques to estimate the amount of information contained in three Krylov-space observables: the spread complexity , the discrete Wigner negativity , and the normalized negativity , where is the survival amplitude. We study thermofield-double evolutions on GUE, GOE and Poisson spectra, and on the integrable Krylov chain of a two-dimensional CFT, primary with Lanczos coefficients . To introduce chaos we add a GUE random matrix to the integrable chain, , where is its spectral half-width. Either or alone determines the thermofield temperature, with . However, neither can reconstruct the fine structure of the spectral form factor. In the integrable sector all three observables carry the same information. When we turn on chaos an asymmetry appears: predicts better than predicts . This gap grows from to , while the same gap for the raw negativity decays to zero. Thus we conclude the extra information comes from the survival amplitude and carries it while can still be recovered from . We derive a lower bound on this gap, set by the fraction of the variance of that comes from .
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