{"id":"https://openalex.org/W2016860894","doi":"https://doi.org/10.1088/0026-1394/48/5/022","title":"The87Sr optical frequency standard at PTB","display_name":"The87Sr optical frequency standard at PTB","publication_year":2011,"publication_date":"2011-09-12","ids":{"openalex":"https://openalex.org/W2016860894","doi":"https://doi.org/10.1088/0026-1394/48/5/022","mag":"2016860894"},"language":"en","primary_location":{"id":"doi:10.1088/0026-1394/48/5/022","doi":"https://doi.org/10.1088/0026-1394/48/5/022","is_oa":true,"landing_page_url":"https://doi.org/10.1088/0026-1394/48/5/022","pdf_url":"https://iopscience.iop.org/article/10.1088/0026-1394/48/5/022/pdf","source":{"id":"https://openalex.org/S7291761","display_name":"Metrologia","issn_l":"0026-1394","issn":["0026-1394","1681-7575"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["anvur-scientific","cwts-core","dongbi-b","jufo-2","norway-1","poland-70","russia-white-list-2"],"host_organization":"https://openalex.org/P4310320083","host_organization_name":"IOP Publishing","host_organization_lineage":["https://openalex.org/P4310320083","https://openalex.org/P4310311669"],"host_organization_lineage_names":["IOP Publishing","Institute of Physics"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Metrologia","raw_type":"journal-article"},"volume":null,"type":"article","is_traditional":true,"indexed_in":["arxiv","crossref","datacite"],"open_access":{"is_oa":true,"oa_status":"bronze","oa_url":"https://iopscience.iop.org/article/10.1088/0026-1394/48/5/022/pdf","any_repository_has_fulltext":true},"authorships":[{"author_position":"first","author":{"id":null,"display_name":"St Falke","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"St Falke","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"H Schnatz","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"H Schnatz","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"J S R Vellore Winfred","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"J S R Vellore Winfred","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"Th Middelmann","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"Th Middelmann","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"St Vogt","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"St Vogt","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5004284842","display_name":"S. Weyers","orcid":"https://orcid.org/0000-0003-4484-6481","observed_orcids":["https://orcid.org/0000-0003-4484-6481"]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"S Weyers","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"B Lipphardt","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"B Lipphardt","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":null,"display_name":"G Grosche","orcid":null,"observed_orcids":[]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"G Grosche","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5023643465","display_name":"F. Riehle","orcid":"https://orcid.org/0000-0002-3348-1539","observed_orcids":["https://orcid.org/0000-0002-3348-1539"]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"F Riehle","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"middle","author":{"id":"https://openalex.org/A5061191199","display_name":"Uwe Sterr","orcid":"https://orcid.org/0000-0001-5661-769X","observed_orcids":["https://orcid.org/0000-0001-5661-769X"]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"U Sterr","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]},{"author_position":"last","author":{"id":"https://openalex.org/A5007647469","display_name":"Christian Lisdat","orcid":"https://orcid.org/0000-0002-4705-8854","observed_orcids":["https://orcid.org/0000-0002-4705-8854"]},"institutions":[{"id":"https://openalex.org/I1285933455","display_name":"Physikalisch-Technische Bundesanstalt","ror":"https://ror.org/05r3f7h03","country_code":"DE","type":"government","lineage":["https://openalex.org/I1285933455","https://openalex.org/I4210136623"]}],"countries":["DE"],"is_corresponding":false,"raw_author_name":"Ch Lisdat","raw_affiliation_strings":["Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany"],"raw_orcid":null,"affiliations":[{"raw_affiliation_string":"Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany","institution_ids":["https://openalex.org/I1285933455"]}]}],"institutions":[],"countries_distinct_count":1,"institutions_distinct_count":1,"corresponding_author_ids":[],"corresponding_institution_ids":["https://openalex.org/I1285933455"],"apc_list":{"value":3325,"currency":"USD","value_usd":3325},"apc_paid":null,"fwci":8.755,"has_fulltext":true,"cited_by_count":133,"citation_normalized_percentile":{"value":0.98652481,"is_in_top_1_percent":false,"is_in_top_10_percent":true},"cited_by_percentile_year":{"min":95,"max":100},"biblio":{"volume":"48","issue":"5","first_page":"399","last_page":"407"},"is_retracted":false,"is_paratext":false,"is_xpac":false,"primary_topic":{"id":"https://openalex.org/T12004","display_name":"Advanced Frequency and Time Standards","score":1.0,"subfield":{"id":"https://openalex.org/subfields/3107","display_name":"Atomic and Molecular Physics, and Optics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},"topics":[{"id":"https://openalex.org/T12004","display_name":"Advanced Frequency and Time Standards","score":1.0,"subfield":{"id":"https://openalex.org/subfields/3107","display_name":"Atomic and Molecular Physics, and Optics"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T11890","display_name":"Scientific Measurement and Uncertainty Evaluation","score":0.0,"subfield":{"id":"https://openalex.org/subfields/3105","display_name":"Instrumentation"},"field":{"id":"https://openalex.org/fields/31","display_name":"Physics and Astronomy"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}},{"id":"https://openalex.org/T12300","display_name":"Advanced Electrical Measurement Techniques","score":0.0,"subfield":{"id":"https://openalex.org/subfields/2208","display_name":"Electrical and Electronic Engineering"},"field":{"id":"https://openalex.org/fields/22","display_name":"Engineering"},"domain":{"id":"https://openalex.org/domains/3","display_name":"Physical Sciences"}}],"keywords":[{"id":"https://openalex.org/keywords/strontium-87","display_name":"strontium-87","score":0.8759999871253967},{"id":"https://openalex.org/keywords/optical-frequency-standard","display_name":"optical frequency standard","score":0.9449999928474426},{"id":"https://openalex.org/keywords/optical-clock-transition","display_name":"optical clock transition","score":0.5730000138282776},{"id":"https://openalex.org/keywords/one-dimensional-optical-lattice","display_name":"one-dimensional optical lattice","score":0.8619999885559082},{"id":"https://openalex.org/keywords/femtosecond-optical-frequency-comb","display_name":"femtosecond optical frequency comb","score":0.7609999775886536},{"id":"https://openalex.org/keywords/cesium-fountain-clock","display_name":"cesium fountain clock","score":0.8759999871253967},{"id":"https://openalex.org/keywords/atomic-clocks","display_name":"atomic clocks","score":0.4020000100135803}],"concepts":[{"id":"https://openalex.org/C2986204303","wikidata":"https://www.wikidata.org/wiki/Q1455602","display_name":"Optical frequency comb","level":3,"score":0.5956000089645386},{"id":"https://openalex.org/C121332964","wikidata":"https://www.wikidata.org/wiki/Q413","display_name":"Physics","level":0,"score":0.5806999802589417},{"id":"https://openalex.org/C131221115","wikidata":"https://www.wikidata.org/wiki/Q362396","display_name":"Frequency standard","level":2,"score":0.5429999828338623},{"id":"https://openalex.org/C120665830","wikidata":"https://www.wikidata.org/wiki/Q14620","display_name":"Optics","level":1,"score":0.5321999788284302},{"id":"https://openalex.org/C3018695096","wikidata":"https://www.wikidata.org/wiki/Q11652","display_name":"Frequency dependence","level":2,"score":0.41690000891685486},{"id":"https://openalex.org/C2778379427","wikidata":"https://www.wikidata.org/wiki/Q483453","display_name":"Fountain","level":2,"score":0.365200012922287},{"id":"https://openalex.org/C196597080","wikidata":"https://www.wikidata.org/wiki/Q227467","display_name":"Atomic clock","level":2,"score":0.34860000014305115},{"id":"https://openalex.org/C2776359362","wikidata":"https://www.wikidata.org/wiki/Q2145286","display_name":"Representation (politics)","level":3,"score":0.33410000801086426},{"id":"https://openalex.org/C184779094","wikidata":"https://www.wikidata.org/wiki/Q26383","display_name":"Atomic physics","level":1,"score":0.3206999897956848},{"id":"https://openalex.org/C2984878632","wikidata":"https://www.wikidata.org/wiki/Q5502879","display_name":"Frequency shift","level":2,"score":0.3075000047683716},{"id":"https://openalex.org/C122348159","wikidata":"https://www.wikidata.org/wiki/Q5502869","display_name":"Frequency drift","level":4,"score":0.3019999861717224},{"id":"https://openalex.org/C194232998","wikidata":"https://www.wikidata.org/wiki/Q1606712","display_name":"Transition (genetics)","level":3,"score":0.2953999936580658},{"id":"https://openalex.org/C30475298","wikidata":"https://www.wikidata.org/wiki/Q909554","display_name":"Computational physics","level":1,"score":0.2773999869823456},{"id":"https://openalex.org/C192562407","wikidata":"https://www.wikidata.org/wiki/Q228736","display_name":"Materials science","level":0,"score":0.27090001106262207},{"id":"https://openalex.org/C129404179","wikidata":"https://www.wikidata.org/wiki/Q1469765","display_name":"Optical communication","level":2,"score":0.26669999957084656},{"id":"https://openalex.org/C97118885","wikidata":"https://www.wikidata.org/wiki/Q565636","display_name":"Frequency analysis","level":2,"score":0.2644999921321869},{"id":"https://openalex.org/C146002875","wikidata":"https://www.wikidata.org/wiki/Q1074289","display_name":"Frequency multiplier","level":3,"score":0.26420000195503235},{"id":"https://openalex.org/C123919525","wikidata":"https://www.wikidata.org/wiki/Q761942","display_name":"Frequency deviation","level":3,"score":0.2614000141620636}],"mesh":[],"locations_count":3,"locations":[{"id":"doi:10.1088/0026-1394/48/5/022","doi":"https://doi.org/10.1088/0026-1394/48/5/022","is_oa":true,"landing_page_url":"https://doi.org/10.1088/0026-1394/48/5/022","pdf_url":"https://iopscience.iop.org/article/10.1088/0026-1394/48/5/022/pdf","source":{"id":"https://openalex.org/S7291761","display_name":"Metrologia","issn_l":"0026-1394","issn":["0026-1394","1681-7575"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["anvur-scientific","cwts-core","dongbi-b","jufo-2","norway-1","poland-70","russia-white-list-2"],"host_organization":"https://openalex.org/P4310320083","host_organization_name":"IOP Publishing","host_organization_lineage":["https://openalex.org/P4310320083","https://openalex.org/P4310311669"],"host_organization_lineage_names":["IOP Publishing","Institute of Physics"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Metrologia","raw_type":"journal-article"},{"id":"pmh:oai:arXiv.org:1104.4850","doi":null,"is_oa":true,"landing_page_url":"http://arxiv.org/abs/1104.4850","pdf_url":"https://arxiv.org/pdf/1104.4850","source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":"2331-8422","issn":["2331-8422"],"is_oa":true,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":"submittedVersion","is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"text"},{"id":"doi:10.48550/arxiv.1104.4850","doi":"https://doi.org/10.48550/arxiv.1104.4850","is_oa":true,"landing_page_url":"https://doi.org/10.48550/arxiv.1104.4850","pdf_url":null,"source":{"id":"https://openalex.org/S4306400194","display_name":"arXiv (Cornell University)","issn_l":"2331-8422","issn":["2331-8422"],"is_oa":true,"is_in_doaj":false,"is_core":false,"listed_in":[],"host_organization":"https://openalex.org/I205783295","host_organization_name":"Cornell University","host_organization_lineage":["https://openalex.org/I205783295"],"host_organization_lineage_names":[],"type":"repository"},"license":null,"license_id":null,"version":null,"is_accepted":false,"is_published":false,"raw_source_name":null,"raw_type":"article-journal"}],"best_oa_location":{"id":"doi:10.1088/0026-1394/48/5/022","doi":"https://doi.org/10.1088/0026-1394/48/5/022","is_oa":true,"landing_page_url":"https://doi.org/10.1088/0026-1394/48/5/022","pdf_url":"https://iopscience.iop.org/article/10.1088/0026-1394/48/5/022/pdf","source":{"id":"https://openalex.org/S7291761","display_name":"Metrologia","issn_l":"0026-1394","issn":["0026-1394","1681-7575"],"is_oa":false,"is_in_doaj":false,"is_core":true,"listed_in":["anvur-scientific","cwts-core","dongbi-b","jufo-2","norway-1","poland-70","russia-white-list-2"],"host_organization":"https://openalex.org/P4310320083","host_organization_name":"IOP Publishing","host_organization_lineage":["https://openalex.org/P4310320083","https://openalex.org/P4310311669"],"host_organization_lineage_names":["IOP Publishing","Institute of Physics"],"type":"journal"},"license":null,"license_id":null,"version":"publishedVersion","is_accepted":true,"is_published":true,"raw_source_name":"Metrologia","raw_type":"journal-article"},"sustainable_development_goals":[],"study_designs":[],"awards":[],"funders":[],"has_content":{"pdf":true,"grobid_xml":true},"content_urls":{"pdf":"https://content.openalex.org/works/W2016860894.pdf","grobid_xml":"https://content.openalex.org/works/W2016860894.grobid-xml"},"referenced_works_count":47,"referenced_works":["https://openalex.org/W9276525","https://openalex.org/W1480563975","https://openalex.org/W1857848356","https://openalex.org/W1978965342","https://openalex.org/W1979599337","https://openalex.org/W1992373949","https://openalex.org/W1995840092","https://openalex.org/W1995943152","https://openalex.org/W1997269293","https://openalex.org/W2001888213","https://openalex.org/W2002925059","https://openalex.org/W2007132189","https://openalex.org/W2009958141","https://openalex.org/W2011259395","https://openalex.org/W2015867533","https://openalex.org/W2017837727","https://openalex.org/W2020607380","https://openalex.org/W2021909579","https://openalex.org/W2025458672","https://openalex.org/W2027142374","https://openalex.org/W2031979987","https://openalex.org/W2034193704","https://openalex.org/W2047616469","https://openalex.org/W2053610669","https://openalex.org/W2053686798","https://openalex.org/W2057605851","https://openalex.org/W2061473905","https://openalex.org/W2066746329","https://openalex.org/W2073489541","https://openalex.org/W2076039468","https://openalex.org/W2077256377","https://openalex.org/W2080095863","https://openalex.org/W2084144772","https://openalex.org/W2084431730","https://openalex.org/W2090609555","https://openalex.org/W2121832766","https://openalex.org/W2124704441","https://openalex.org/W2130167976","https://openalex.org/W2131232467","https://openalex.org/W2131819852","https://openalex.org/W2145272130","https://openalex.org/W2145804907","https://openalex.org/W2155147465","https://openalex.org/W2315214008","https://openalex.org/W2735623653","https://openalex.org/W2763613630","https://openalex.org/W4243403748"],"related_works":["https://openalex.org/W1969928411","https://openalex.org/W2121832766","https://openalex.org/W3026166183","https://openalex.org/W7034136547","https://openalex.org/W1557463547","https://openalex.org/W2103870848","https://openalex.org/W1965276912","https://openalex.org/W4313539443","https://openalex.org/W7096346717","https://openalex.org/W2084144772"],"abstract_inverted_index":{"With":[0],"87":[1],"Sr":[2,68],"atoms":[3],"confined":[4],"in":[5],"a":[6,46,74],"one-dimensional":[7],"optical":[8,14,69],"lattice,":[9],"the":[10,13,43,62,83,89,100,106,110,113],"frequency":[11,39,57,70,92],"of":[12,45,51,77,88,102,109],"clock":[15,65],"transition":[16,38,91,104],"5s":[17],"2":[18],"1":[19],"S":[20],"0":[21,25],"\u20135s5p":[22],"3":[23],"P":[24],"has":[26],"been":[27],"determined":[28],"to":[29,82],"be":[30],"429":[31],"228":[32],"004":[33],"229":[34],"872.9(5)":[35],"Hz.":[36],"The":[37,67,86],"was":[40,58],"measured":[41,59,90],"with":[42,73,93,112],"help":[44],"femtosecond-frequency":[47],"comb":[48],"against":[49],"one":[50],"Physikalisch-Technische":[52],"Bundesanstalt":[53],"(PTB's)":[54],"H-masers":[55],"whose":[56],"simultaneously":[60],"by":[61],"PTB":[63],"Cs-fountain":[64],"CSF1.":[66],"standard":[71],"contributes":[72],"fractional":[75],"uncertainty":[76],"1.5":[78],"\u00d7":[79],"10":[80],"\u221216":[81],"total":[84],"uncertainty.":[85,116],"agreement":[87],"previous":[94],"measurements":[95],"at":[96],"other":[97],"institutes":[98],"supports":[99],"status":[101],"this":[103],"as":[105],"secondary":[107],"representation":[108],"second":[111],"currently":[114],"smallest":[115]},"counts_by_year":[{"year":2026,"cited_by_count":3},{"year":2025,"cited_by_count":3},{"year":2024,"cited_by_count":9},{"year":2023,"cited_by_count":5},{"year":2022,"cited_by_count":3},{"year":2021,"cited_by_count":3},{"year":2020,"cited_by_count":11},{"year":2019,"cited_by_count":5},{"year":2018,"cited_by_count":9},{"year":2017,"cited_by_count":5},{"year":2016,"cited_by_count":10},{"year":2015,"cited_by_count":11},{"year":2014,"cited_by_count":16},{"year":2013,"cited_by_count":19},{"year":2012,"cited_by_count":19}],"updated_date":"2026-11-07T11:25:07.637180","created_date":"2016-06-24T00:00:00"}
