Noise-enhanced quantum clocks and global field sensors

TL;DR

This paper demonstrates that incoherent quantum dynamics can enhance the precision of quantum clocks and sensors by increasing quantum Fisher information, leading to improved estimation of time intervals and global fields.

Contribution

It introduces the concept that incoherent dynamics can serve as a metrological resource, providing a new approach to quantum sensing beyond coherent quantum states.

Findings

Incoherent dynamics additively increase quantum Fisher information.

Noise can improve the accuracy of time and frequency estimation.

Protocols with incoherent dynamics outperform traditional methods in certain regimes.

Abstract

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.