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. Regards Paul WB8TSL
On Wed, Nov 2, 2016 at 6:51 AM, Attila Kinali <[email protected]> wrote: > On Wed, 02 Nov 2016 10:02:53 +0000 > "Poul-Henning Kamp" <[email protected]> wrote: > > > In message <[email protected]>, 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 > defects: > > "Timekeeping with electron spin states in diamond", by Hodges, Yao, > Maclaurin, Rasogi, Lukin, Englund, 2013 > http://link.aps.org/doi/10.1103/PhysRevA.87.032118 > https://arxiv.org/abs/1109.3241 > > "Solid-state electronic spin coherence time approaching one second", > by Bar-Gill, Pham, Jarmola, Budker, Walsworth, 2013 > http://dx.doi.org/10.1038/ncomms2771 > > "High-resolution correlation spectroscopy of 13C spins near a > nitrogen-vacancy centre in diamond", by Laraoui, Dolde, Burk, Reinhard, > Wrachtrup, Meriles, 2013, > http://dx.doi.org/10.1038/ncomms2685 > > 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 > influenced > by them. Any change in distance or strain directly affects the energy > levels. > > 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 > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
