[time-nuts] Cs tube pics
paulswedb at gmail.com
Wed Nov 2 11:34:42 EDT 2016
A comment to the thread.
Desired a C, obtained a C. Discovered they take care, feeding and power.
Mine is after all a rag-tag C.
So thats why they run them on UPS systems....
Anyhow happy that I have one and learned so much.
But for a large group of time-nuts GPSDO may simply be good enough.
No concerns for the C's running out....
So desire is good education is great, but a consideration in reality.
On Wed, Nov 2, 2016 at 6:51 AM, Attila Kinali <attila at kinali.ch> wrote:
> On Wed, 02 Nov 2016 10:02:53 +0000
> "Poul-Henning Kamp" <phk at phk.freebsd.dk> wrote:
> > In message <20161102104103.0c58d35a72b7b36253b3d6b2 at kinali.ch>, Attila
> Kinali writes:
> > >I still would like to try to build my own atomic clock at some point,
> > >even if it would be a quite costly, and a many years project.
> > If you like lasers, build an ion trap.
> > If you only like lasers a little bit, build an optically pumped standard.
> > If you *really* like lasers, build a fountain.
> If you *really*really* like lasers build an neutral atom optical clock :-)
> A fountain is a quite intricate design. Beside doing the MOT one needs
> to launch the atoms in a precisely determined direction with precisely
> controlled speed, such that they pass trough the cavity with a constant
> timing. If multiple cavities are used, the alignment is sligtly more
> difficult (not just launching straigth up, but in a parabola and mistakes
> make the atoms get lost completely, and not just arrive early/late).
> It might be easier to just let the atoms fall freely within the cavity
> and do the Ramsey probing using lasers instead of a microwave cavity.
> Of course this reduces the time avaible and induces a Doppler shift which
> needs to be calculated and compensated.
> > The one thing nobody has done or even tried yet, (as far as I know),
> > is optically excite a solid crystal.
> This has been done. Ok, not the whole crystal, but single atoms within
> the crystall. The most popular is probably diamond nitrogen vacancy
> "Timekeeping with electron spin states in diamond", by Hodges, Yao,
> Maclaurin, Rasogi, Lukin, Englund, 2013
> "Solid-state electronic spin coherence time approaching one second",
> by Bar-Gill, Pham, Jarmola, Budker, Walsworth, 2013
> "High-resolution correlation spectroscopy of 13C spins near a
> nitrogen-vacancy centre in diamond", by Laraoui, Dolde, Burk, Reinhard,
> Wrachtrup, Meriles, 2013,
> But these all suffer from one problem: mounting and temperature effects.
> Because the nitrogen atom is not in free space, but bond trough its
> valence electrons to the surrounding carbon atoms, it is directly
> by them. Any change in distance or strain directly affects the energy
> 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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