Improved absolute clock stability by the joint interrogation of two atomic ensembles

Year: 2022

Authors: Li W., Wu S.; Smerzi A., Pezzè L.

Autors Affiliation: Shenzhen Technol Univ, Shenzhen Key Lab Ultraintense Laser & Adv Mat Tec, Ctr Adv Mat Diagnost Technol, Shenzhen 518118, Peoples R China; Shenzhen Technol Univ, Coll Engn Phys, Shenzhen 518118, Peoples R China; Southern Univ Sci & Technol, Guangdong Prov Key Laoratory Quantum Sci & Engn, Shenzhen 518055, Peoples R China; CNR, INO, QSTAR, Largo Enrico Fermi 2, I-50125 Florence, Italy; LENS, Largo Enrico Fermi 2, I-50125 Florence, Italy; Shanxi Univ, Inst Theoret Phys, Taiyuan 030006, Peoples R China; Shanxi Univ, Dept Phys, Taiyuan 030006, Peoples R China.

Abstract: Improving the clock stability is of fundamental importance for the development of quantum-enhanced metrology. One of the main limitations arises from the randomly fluctuating local oscillator (LO) frequency, which introduces “phase slips” for long interrogation times and hence the failure of the frequency-feedback loop. Here we propose a strategy to improve the stability of atomic clocks by interrogating two atomic ensembles sharing the same LO. The two ensembles are prepared in coherent spin states pointing along orthogonal directions in the Bloch sphere. While standard Ramsey interrogation can only determine phases unambiguously in the interval [-p/2,p/2], the joint interrogation allows for an extension to [-p,p], resulting in a relaxed restriction of the Ramsey time and improvement of absolute clock stability. Theoretical predictions are supported by ab initio numerical simulation for white and correlated LO noise. While our basic protocol uses uncorrelated atoms, we further extended it to include spin-squeezing and further improving the scaling of clock stability with the number of atoms. Our protocol can be readily tested in current state-of-the-art experiments.

Journal/Review: PHYSICAL REVIEW A

Volume: 105 (5)      Pages from: 053116-1  to: 053116-15

More Information: We thank A. Bertolldi, K. Hammerer, F. Levi, M. Schulte, and M. Tarallo for discussions. We acknowledge funding of the project EMPIR-USOQS, EMPIR projects are cofunded by the European Unions Horizon2020 research and innovation program and the EMPIR Participating States. We also acknowledge support by the H2020 QuantERA ERA-NET co-fund QCLOCKS. This research was supported by the National Key R&D Program of China (Grant No. 2017YFA0304500) , National Natural Science Foundation of China (Grant No. 11874247) , 111 project (Grant No. D18001) , the Hundred Talent Program of the Shanxi Province (2018).
KeyWords: quantum projection noise; states
DOI: 10.1103/PhysRevA.105.053116

ImpactFactor: 2.900
Citations: 5
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