2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/162560We perform an information-theoretical analysis of quantum measurement processes and obtain the global information balance in quantum measurements, in the form of a closed chain equation for quantum mutual entropies. Our balance provides a tight and general entropic information-disturbance trade-off, and explains the physical mechanism underlying it. Finally, the single-outcome case, that is, the case of measurements with post-selection, is briefly discussed.Final version to appear on Physical Review LettersQuantum Physicstext