Josephson voltage standard

{c}
{title2=JVS}
{wiki}

The most practical/precise volt standard.

It motivated the definition of the <ampere in the 2019 redefinition of the SI base units>

Good <NIST> articles about it:
* https://www.nist.gov/news-events/news/2013/04/primary-voltage-standard-whole-world[A Primary Voltage Standard for the Whole World]
   (2013)
 (https://web.archive.org/web/20190410011041/https://www.nist.gov/news-events/news/2013/04/primary-voltage-standard-whole-world[archive])
* https://www.nist.gov/pml/history-nist-quantum-voltage-standards[History of NIST Quantum Voltage Standards (2011-2022)]

The wiki page https://en.wikipedia.org/wiki/Josephson_voltage_standard contains amazing schematics of the device, apparently made by the <US Government>.

\Image[https://upload.wikimedia.org/wikipedia/commons/2/2b/Layout_and_Schematic_of_JVS_Chip.jpg]
{title=Schematic of a typical <Josephson voltage standard> chip}
{height=600}

\Image[https://web.archive.org/web/20241201074611im_/https://www.nist.gov/sites/default/files/styles/480_x_480_limit/public/images/pml/div686/devices/sam-switch900.png?itok=OyCJl26y]
{title=Sam Benz demonstrating the equipment required the voltage standard}
{height=600}
{source=https://www.nist.gov/news-events/news/2013/04/primary-voltage-standard-whole-world}

\Video[https://www.youtube.com/watch?v=VoRab8U2eS0]
{title=The evolution of voltage metrology to the latest generation of JVSs by Alain Rüfenacht}
{description=
Talk given in 2023. The speaker is from <NIST>, and the talk was hosted by the <BIPM>. Fantastic talk.
* https://youtu.be/VoRab8U2eS0?t=354 the desired output voltage is 10V
* https://youtu.be/VoRab8U2eS0?t=475 lists the three most commonly used 10V implementations currently:
  * <Japanese> one by <AIST>
  * <American> one by <NIST>
  * <German> one by <PTB>
}

\Video[https://www.youtube.com/watch?v=VoRab8U2eS0]
{title=Technical aspects of realizing the DC volt in the laboratory with a JVS by Stéphane Solve}
{description=
Talk given in 2023. The speaker is from <BIPM>, and the talk was hosted by the <BIPM>. Fantastic talk.
* https://youtu.be/6pgGNJby1lw?t=296 gives the experimental setup used to compare two different references. Notably it involves a <nanovoltmeter>
}


 Josephson voltage standard