Comparison of the INMETRO and NIST Josephson Voltage Standards (part of the ongoing regional key comparison SIM.EM.BIPM-K10.b.1)

Abstract

A direct comparison of the 10 V Josephson Voltage Standards (JVS) of the National Institute of Standards and Technology (NIST), USA, and the Instituto Nacional de Metrologia, Normalização e Qualidade Industrial (INMETRO), Brazil, was made in June 2009. The process consisted of two comparisons, first using the NIST CJVS's measuring system (hardware and software) to measure the 10 V reference voltage provided by the INMETRO JVS and then using the INMETRO JVS's measuring system to measure the 10 V reference voltage provided by the NIST CJVS. The results of the two comparisons were in agreement to within 1.1 nV and their mean indicated that the difference between the two JVSs at 10 V was 0.54 nV with a combined standard uncertainty of 1.48 nV or a relative standard uncertainty of 1.48 parts in 1010.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Bilateral comparison of dc voltage at 10 V between UTE and INMETRO

“…Three key-comparisons, linked to the above mentioned ones were performed in the Inter-American Metrology System (SIM) Regional Metrology Organization, so far: the SIM.EM.BIPM-K11.b (in 2006, using Zeners for an indirect on-site comparison, resulting in 4.32 parts in 10 9 of expanded uncertainty, k=2) [5], the SIM.EM.BIPM-K10.b (in 2007, in a direct on-site JVS comparison, reaching 2.07 parts in 10 10 of expanded uncertainty, k=2) [6] and the SIM.EM.BIPM-K10.b.1 (in 2009, in a direct on-site JVS comparison, reaching 1.48 parts in 10 10 of expanded uncertainty, k=2) [7]. There are no records of off-site indirect (via Zeners) JVS key-comparison within the SIM, like the most recent one, performed between the BIPM and the KEBS (Kenya), in 2017 (BIPM.EM-K11.a&b, which resulted in 1.55 parts in 10 7 of expanded uncertainty, k=2) [8].…”

Design e caracterização de junções ScS em nióbio

“…Desde sua previsão em 1962 [1] e rápida confirmação em 1963 [2], o efeito Josephson tem desempenhado um importante papel na ciência, estando presente em estudos atuais de dinâmica de sólitons [3], implementação de bits quânticos [4], metrologia [6,5], supercondutividade de alta temperatura crítica [7] e mecânica quântica de variáveis macroscópicas [8], entre outros exemplos.…”

“…Até onde sabemos, apenas dois grupos tentaram desenvolver trabalhos nessa linha. Um deles no Instituto Nacional de Metrologia, o INMETRO, que, em colaboração com o NIST (National Institute of Standards and Technology, EUA), estuda dispositivos baseados em redes de junções Josephsons capazes de gerar a definição mais precisa que a humanidade conhece do volt [5]. O outro grupo, trabalhando no Centro Brasileiro de Pesquisas Físicas (CBPF), explorou outra capacidade de medição com alta sensibilidade disponibilizada pelo efeito Josephson, agora no campo do magnetismo [9].…”