Coherence and quantum correlations measure sensitivity to dephasing channels
Benjamin Yadin, Pieter Bogaert, Cristian E. Susa, Davide Girolami · Physical Review A · 2019
We introduce measures of quantum coherence as the speed of evolution of a system under decoherence. That is, coherence is the ability to estimate a dephasing channel, quantified by the quantum Fisher information. We extend the analysis to interferometric noise estimation, proving that quantum discord is the minimum sensitivity to local dephasing. A physically motivated set of free operations for discord is proposed. The amount of discord created by strictly incoherent operations is upper bounded by the initial coherence.