[LEAPSECS] quantum metrology triangle

[Rob Seaman]

Not related to UTC, but here’s an interesting preprint on the final leg of the quantum metrology triangle, namely a direct quantum method for measuring current and calibrating the ampere in terms of the charge of the electron:

	http://arxiv.org/pdf/1312.5669v1.pdf

(The other two legs are the quantum Hall effect for resistance and the Josephson voltage standard.)  This is a step toward implementing the new SI definitions:

	http://en.wikipedia.org/wiki/File:Relations_between_new_SI_units_definitions.png

The SI-second (or perhaps the hertz) is the keystone supporting all the other base units save the mole.

Rob