2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/128006We derive the amount of information retrieved by a quantum measurement in estimating an unknown maximally entangled state, along with the pertaining disturbance on the state itself. The optimal tradeoff between information and disturbance is obtained, and a corresponding optimal measurement is provided.4 pages. Accepted for publication on Physical Review LettersQuantum Physicstext