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Chin. Phys. B, 2026, Vol. 35(1): 010602    DOI: 10.1088/1674-1056/ae1120
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Enhanced timing of a 113 km O-TWTFT link with complex maximum likelihood estimation process

Yu-Chen Fang(方宇辰)1,2,3,†, Jian-Yu Guan(管建宇)2,3,†, Qi Shen(沈奇)1,2,3, Jin-Jian Han(韩金剑)1,2,3, Lei Hou(侯磊)2,3, Meng-Zhe Lian(连蒙浙)1,2,3, Yong Wang(王勇)4, Wei-Yue Liu(刘蔚悦)2,3,5, Ji-Gang Ren(任继刚)1,2,3, Cheng-Zhi Peng(彭承志)1,2,3, Qiang Zhang(张强)1,2,3, Hai-Feng Jiang(姜海峰)1,2,3,‡, and Jian-Wei Pan(潘建伟)1,2,3
1 Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China;
2 Shanghai Research Center for Quantum Sciences and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China;
3 Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China;
4 Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi 830011, China;
5 Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China
Abstract  Optical two-way time-frequency transfer (O-TWTFT), utilizing optical frequency comb carriers and linear optical sampling, effectively enables space-to-ground optical frequency standard comparisons. Previously reported detection sensitivities of O-TWTFTs were typically in the nanoWatt level, necessitating high-power optical frequency combs to compensate for significant losses in high-orbit satellite-to-ground passes. Such hardware-based solutions, while effective, tend to be costly. This paper presents a novel data post-processing algorithm to enhance sensitivity. Unlike previous timing methods, which depend solely on optical phase data and discard intensity information — resulting in elevated errors, especially under low-reception power, our approach employs complex least squares (CLS) estimation in the complex frequency domain. By preserving all intermediate data and avoiding noise from phase unwrapping, it achieves superior sensitivity and accuracy. Experiments over a 113-kilometer free-space link validate the algorithm’s robustness, delivering a detection sensitivity of 0.1 nanoWatts — over tenfold better than prior techniques — despite a 100-decibel link loss, comparable to Earth-Moon optical links.
Keywords:  optical time-frequency transfer      linear optical sampling      frequency comb      complex least squares  
Received:  10 September 2025      Revised:  25 September 2025      Accepted manuscript online:  09 October 2025
PACS:  06.30.Ft (Time and frequency)  
  42.62.Eh (Metrological applications; optical frequency synthesizers for precision spectroscopy)  
  42.79.Sz (Optical communication systems, multiplexers, and demultiplexers?)  
Fund: This research was supported by the National Key Research and Development Programme of China (Grant Nos. 2020YFC2200103 and 2020YFA0309800), the National Natural Science Foundation of China (Grant No. T2125010), Strategic Priority Research Programme of Chinese Academy of Sciences (Grant No. XDB35030000), Anhui Initiative in Quantum Information Technologies (Grant No. AHY010100), Key R&D Plan of Shandong Province (Grant No. 2021ZDPT01), Shanghai Municipal Science and Technology Major Project (Grant No. 2019SHZDZX01), and Innovation Programme for Quantum Science and Technology (Grant Nos. 2021ZD0300100, 2021ZD0300300, and 2021ZD0300903).
Corresponding Authors:  Hai-Feng Jiang     E-mail:  hjiang1@ustc.edu.cn

Cite this article: 

Yu-Chen Fang(方宇辰), Jian-Yu Guan(管建宇), Qi Shen(沈奇), Jin-Jian Han(韩金剑), Lei Hou(侯磊), Meng-Zhe Lian(连蒙浙), Yong Wang(王勇), Wei-Yue Liu(刘蔚悦), Ji-Gang Ren(任继刚), Cheng-Zhi Peng(彭承志), Qiang Zhang(张强), Hai-Feng Jiang(姜海峰), and Jian-Wei Pan(潘建伟) Enhanced timing of a 113 km O-TWTFT link with complex maximum likelihood estimation process 2026 Chin. Phys. B 35 010602

[1] Brewer S M, Chen J S, Hankin A M, Clements E R, Chou C W, Wineland D J, Hume D B and Leibrandt D R 2019 Phys. Rev. Lett. 123 033201
[2] Bothwell T, Kedar D, Oelker E, Robinson J M, Bromley S L, Tew W L, Ye J and Kennedy C J 2019 Metrologia 56 065004
[3] Nicholson T L, Campbell S, Hutson R, Marti G E, Bloom B, McNally R L, Zhang W, Barrett M, Safronova M S, Strouse G, et al. 2015 Nat. Commun. 6 6896
[4] Huntemann N, Sanner C, Lipphardt B, Tamm C and Peik E 2016 Phys. Rev. Lett. 116 063001
[5] Aeppli A, Kim K, Warfield W, Safronova M S and Ye J 2024 Phys. Rev. Lett. 133 023401
[6] Dimarcq N, Gertsvolf M, Mileti G, Bize S, Oates C, Peik E, Calonico D, Ido T, Tavella P, Meynadier F, et al. 2024 Metrologia 61 012001
[7] Mehlstaubler T E, Grosche G, Lisdat C, Schmidt P O and Denker H 2018 Reports on Progress in Physics 81 064401
[8] Lisdat C, Grosche G, Quintin N, Shi C, Raupach S, Grebing C, Nicolodi D, Stefani F, Al-Masoudi A, Dorscher S, et al. 2016 Nat. Commun. 7 12443
[9] Exertier P, Samain E, Bonnefond P and Guillemot P 2010 Advances in Space Research 46 1559
[10] Exertier P, Samain E, Martin N, Courde C, Laas-Bourez M, Foussard C and Guillemot P 2014 Advances in Space Research 54 2371
[11] Giorgetta F R, Swann W C, Sinclair L C, Baumann E, Coddington I and Newbury N R 2013 Nat. Photonics 7 434
[12] Shen Q, Guan J Y, Ren J G, Zeng T, Hou L, Li M, Cao Y, Han J J, Lian M Z, Chen Y W, et al. 2022 Nature 610 661
[13] Caldwell E D, Sinclair L C, Newbury N R and Deschenes J D 2022 Nature 610 667
[14] Caldwell E D, Deschenes J D, Ellis J, Swann W C, Stuhl B K, Bergeron H, Newbury N R and Sinclair L C 2023 Nature 618 721
[15] Kong L, Cui K, Shi J, Zhu M and Li S 2022 Journal of Lightwave Technology 40 252
[16] Itoh K 1982 Applied Optics 21 2470
[17] Shen Q, Guan J Y, Zeng T, Lu Q M, Huang L, Cao Y, Chen J P, Tao T Q, Wu J C, Hou L, et al. 2021 Optica 8 471
[18] Walsh M, Guay P and Genest J 2023 APL Photonics 8 071302
[19] Oelker E, Hutson R, Kennedy C, Sonderhouse L, Bothwell T, Goban A, Kedar D, Sanner C, Robinson J, Marti G, et al. 2019 Nat. Photonics 13 714
[20] Schioppo M, Brown R C, McGrew W F, Hinkley N, Fasano R J, Beloy K, Yoon T, Milani G, Nicolodi D, Sherman J, et al. 2017 Nat. Photonics 11 48
[21] Ellis J L, Bodine M I, Swann W C, Stevenson S A, Caldwell E D, Sinclair L C, Newbury N R and Deschenes J D 2021 Phys. Rev. Applied 15 034002
[22] Richards M A, et al. 2005 Fundamentals of radar signal processing Vol. 1 (New York: Mcgraw-Hill)
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