Noise-enhanced quantum clocks and global field sensors

I show that incoherent dynamics can lead to metrological advantages in quantum sensing. The results rely on the fact that incoherent dynamics lead to an additive contribution to the quantum Fisher information about time. Such an additive contribution can lead to a decrease in the error of optimal estimation protocols, as implied by the quantum Cram\'er-Rao bound. I characterize regimes in which the estimation of a time interval or a frequency is enhanced by noise, thus identifying cases where incoherent dynamics serve as a metrological resource. I illustrate with protocols that display improved sensing of time intervals or global fields by qubit and photonic sensor networks.