{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T08:31:50Z","timestamp":1787646710853,"version":"build-2736575974"},"reference-count":29,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T00:00:00Z","timestamp":1787616000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62405302"],"award-info":[{"award-number":["62405302"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["62405302"],"award-info":[{"award-number":["62405302"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100020769","name":"National Institute of Metrology of China","doi-asserted-by":"publisher","award":["AKYCX2603"],"award-info":[{"award-number":["AKYCX2603"]}],"id":[{"id":"10.13039\/501100020769","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100020769","name":"National Institute of Metrology of China","doi-asserted-by":"publisher","award":["AKYZD2403-2"],"award-info":[{"award-number":["AKYZD2403-2"]}],"id":[{"id":"10.13039\/501100020769","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100020769","name":"National Institute of Metrology of China","doi-asserted-by":"publisher","award":["AKYKF2601"],"award-info":[{"award-number":["AKYKF2601"]}],"id":[{"id":"10.13039\/501100020769","id-type":"DOI","asserted-by":"publisher"}]},{"award":["AKYCX2603"],"award-info":[{"award-number":["AKYCX2603"]}],"id":[{"id":"https:\/\/ror.org\/05dw0p167","id-type":"ROR","asserted-by":"publisher"}]},{"award":["AKYZD2403-2"],"award-info":[{"award-number":["AKYZD2403-2"]}],"id":[{"id":"https:\/\/ror.org\/05dw0p167","id-type":"ROR","asserted-by":"publisher"}]},{"award":["AKYKF2601"],"award-info":[{"award-number":["AKYKF2601"]}],"id":[{"id":"https:\/\/ror.org\/05dw0p167","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Innovation Program for Quantum Science and Technology","award":["2021ZD0300902"],"award-info":[{"award-number":["2021ZD0300902"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Optical clocks and their associated frequency comparison networks are exceptionally sensitive to microscopic physical variations and thus capable of measuring fundamental physical quantities across diverse applications. In frequency comparison networks, the optical frequency combs (OFCs) act as accurate frequency sensors designed to translate terahertz optical signals down to radio frequency signals for accurate frequency counting. The number of OFC\u2019s comb modes that beat with clock and transfer lasers during remote frequency comparison is indispensable for the calculation of their frequency difference. In this work, with the assistance of a 1542 nm cavity-stabilized laser at Changping campus, the number of comb modes is locally determined with sufficient uncertainty by stepping the comb\u2019s repetition rate. This approach bypasses the technical challenges of simultaneous operation of optical clocks, OFC and fiber-link noise cancelation during long-distance comparison, providing a reliable prerequisite for remote optical clock comparisons.<\/jats:p>","DOI":"10.3390\/s26175360","type":"journal-article","created":{"date-parts":[[2026,8,25]],"date-time":"2026-08-25T08:00:48Z","timestamp":1787644848000},"page":"5360","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Local Determination of Comb Mode Number in Remote Optical Clock Comparison"],"prefix":"10.3390","volume":"26","author":[{"given":"Hao","family":"Liu","sequence":"first","affiliation":[{"name":"Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China"},{"name":"Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2650-4915","authenticated-orcid":false,"given":"Haochen","family":"Tian","sequence":"additional","affiliation":[{"name":"Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100029, China"},{"name":"Hefei National Laboratory, Hefei 230088, China"},{"name":"Key Laboratory of Time Frequency and Gravity Primary Standard, State Administration for Market Regulation, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-8085-4427","authenticated-orcid":false,"given":"Bingkun","family":"Lu","sequence":"additional","affiliation":[{"name":"Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100029, China"},{"name":"Key Laboratory of Time Frequency and Gravity Primary Standard, State Administration for Market Regulation, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiang","family":"Wang","sequence":"additional","affiliation":[{"name":"Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100029, China"},{"name":"Hefei National Laboratory, Hefei 230088, China"},{"name":"Beijing Key Laboratory of Quantum Metrology Technology and Instruments, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7991-2314","authenticated-orcid":false,"given":"Yige","family":"Lin","sequence":"additional","affiliation":[{"name":"Division of Time and Frequency Metrology, National Institute of Metrology, Beijing 100029, China"},{"name":"Hefei National Laboratory, Hefei 230088, China"},{"name":"Beijing Key Laboratory of Quantum Metrology Technology and Instruments, Beijing 100029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1800364","DOI":"10.1002\/andp.201800364","article-title":"The Search for Variation of Fundamental Constants with Clocks","volume":"531","author":"Safronova","year":"2019","journal-title":"Ann. 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