[time-nuts] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference

Attila Kinali attila at kinali.ch
Fri Dec 15 13:00:10 EST 2017


On Fri, 15 Dec 2017 17:17:31 +0100
Mike Cook <michael.cook at sfr.fr> wrote:

> > The original paper in question is [1]. As with the nitrogen vacancy
> > clocks, which also trap nitrogen within a Carbon lattice, these have the
> > drawback of quite high temperature coefficients, Harding et al measured 89ppm/K.
> 
> I wonder if Cs-133 can be inserted into C-60 fullerene? If it could,
> then a primary reference on a chip might be possible.

No, it wouldn't. It isn't the species of atom being used that defines
whether it is a primary standard or not, but rather that it is possible
to exactly calculate the frequency of the output given all disturbances.
It is possible to achieve this with Cs, Rb, Hg, Yb, Sr, ... it just depends
on how you do it.

The problem with the atom-in-fullerene is that the atom is not in 
(a good approximation of) vacuum, as it is surrounded by a molecule
in close proximity. This means the surrounding atoms disturb the electrons
of the probed atom. This is what causes the large temperature dependence.

			Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson


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