Non-Markovian delay-assisted sensing with waveguide-coupled quantum emitters

TL;DR

This paper demonstrates that non-Markovian delay effects in waveguide-coupled quantum emitters can enhance quantum sensing of field gradients by increasing quantum Fisher information through atom-photon quasi-bound states.

Contribution

It reveals how non-Markovian delay and multimode interactions improve the sensitivity of quantum sensors based on waveguide-coupled emitters.

Findings

Quantum Fisher information is enhanced by non-Markovian delay.

Formation of atom-photon quasi-bound states increases information gain.

Multiple spectral modes mediate emitter interactions, boosting sensing capabilities.

Abstract

We show that in a minimal setup of two waveguide-coupled quantum emitters, separated by long distances and subject to an external field, time-delayed feedback can be a resource for sensing field gradients. While the field gradient induces a detuning between the emitters; the large interatomic separations render the system dynamics non-Markovian. We show that the quantum Fisher information (QFI) for estimating the detuning parameter, and thereby the field gradient, is enhanced in the presence of non-Markovian delay. Such an enhancement can be attributed to the formation of atom-photon quasi-bound states that enable the field to interact with the emitters for longer times, thereby gaining more information about their relative detunings. Additionally, in the presence of delay, the interaction between the emitters is mediated via multiple spectral modes of the field, further enhancing the sensing capabilities of the system. Our results establish non-Markovian time-delayed feedback and multimode reservoirs as a resource for distributed quantum sensing with waveguide-coupled quantum emitters.