All expected publications for the precise determination of the Planck and Avogadro constants are now online.
You may find the documents, most of them for free download, in
metrologia:
http://iopscience.iop.org/journal/0026-1394/page/CODATA-2017_adjustment The necessary criterions are fulfilled to the due date of 30th June 2017, obviously:
R1: At least 3 different experiments agree within < 50ppb (7 experiments)
R2: At least 1 experiment is uncertain to < 20ppb (3 experiments)
http://www.bipm.org/utils/common/pdf/SI-roadmap.pdf#page=3I compiled these results in a graph, which is copied from Derek Mullers latest VERITASIUM video, about the redefinition of the kilogram and the NIST-4 Kibble balance.
![](https://www.eevblog.com/forum/metrology/new-kilogram-volt-and-ohm-are-ready-for-si-2018/?action=dlattach;attach=331334;image)
The different numeric results are summarized in this table:
![](https://www.eevblog.com/forum/metrology/new-kilogram-volt-and-ohm-are-ready-for-si-2018/?action=dlattach;attach=331336;image)
A little bit disappointing is the result of the latest PTB measurements, done on new, improved Si - spheres.
The numerical value is a bit far outside, and not overlapping with the other most precise WB experiments, from NIST and NRC.
Anyhow, the elder results from 2015 agree better.
This means, that in a few months time, CODATA 2017 will be published, with adapted values for h, e and N(A) respectively, which will then used for the final fixing of the new kilogram, the Volt and the Ohm, by end of 2018, when the according bipm congress, CGPM, will decide to implement SI-2018. I now believe for certain, that this will happen without any doubts.
These three units, plus the Kelvin, will then have quantum based definitions, with zero uncertainty in the SI.
Currently, Volt and Ohm both have about 0.2 ppm uncertainty, and the prototype kilogram is drifting 0.05 ppm in hundred years, or so.
I'm very excited but also pleased about this outcome, looking forward to the new units.
Frank