GHZ protocols enhance frequency metrology despite spontaneous decay

authored by

Timm Kielinski, Piet O. Schmidt, Klemens Hammerer

Abstract

The use of correlated states and measurements promises improvements in the accuracy of frequency metrology and the stability of atomic clocks. However, developing strategies robust against dominant noise processes remains challenging. We address the issue of decoherence due to spontaneous decay and show that Greenberger-Horne-Zeilinger (GHZ) states, in conjunction with a correlated measurement and nonlinear estimation strategy, achieve gains comparable to fundamental bounds for ensembles of up to 40 atoms. This result is surprising since GHZ states do not provide any enhancement under dephasing noise compared to the standard quantum limit of uncorrelated states. The gain arises from a veto signal, which allows for the detection and mitigation of errors caused by spontaneous emission events. Through comprehensive Monte-Carlo simulations of atomic clocks, we demonstrate the robustness of the GHZ protocol.

Organisation(s)

Institute of Theoretical Physics
Institute of Quantum Optics

External Organisation(s)

National Metrology Institute of Germany (PTB)

Type

Preprint

No. of pages

13

Publication date

17.06.2024

Publication status

E-pub ahead of print

Electronic version(s)

https://doi.org/10.48550/arXiv.2406.11639 (Access: Open)