TY - JOUR

T1 - GHZ protocols enhance frequency metrology despite spontaneous decay

AU - Kielinski, Timm

AU - Schmidt, Piet O.

AU - Hammerer, Klemens

N1 - Publisher Copyright: Copyright © 2024 The Authors, some rights reserved;

PY - 2024/10

Y1 - 2024/10

N2 - 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.

AB - 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.

KW - quant-ph

KW - physics.atom-ph

UR - http://www.scopus.com/inward/record.url?scp=85207724189&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2406.11639

DO - 10.48550/arXiv.2406.11639

M3 - Article

VL - 10

JO - Science advances

JF - Science advances

SN - 2375-2548

IS - 43

M1 - eadr1439

ER -