[time-nuts] Re: Project Great

[Attila Kinali]

On Sun, 28 Nov 2021 14:05:42 -0800
"Lux, Jim" <jim at luxfamily.com> wrote:

> Speaking of which, does anyone have a link to a "current state of the 
> art" graph.

I have not seen one. But most is pretty much the same.
We have OCXOs that do 1e-13, but that's best you can get
commercially[1]. Cs have gotten only marginally better with
optical pumping and detection. H-Masers now bottom out
just a bit over 1e-16[2].

The only thing that changed is that Rb can now reach 1e-13
at 1s and bottom out at 1e-14. But only lab models, not
commercially available[3].

Though, what is missing on this graph are CSO's,
They do <1e-15 over a range from 1s to 10k[4]. 

			Attila Kinali

[1] Rakon HSO14 
https://www.rakon.com/news/ultra-stable-oscillators-hso14-and-hso13-for-ground-based-applications

[2] T4 Science iMaser 3000
https://www.t4science.ch/products/imaser3000/

[3] "Long-Term stability analysis toward <1e-14 level for
highly compact POP Rb cell atomic clock", by Almat et al. 2020

[4] "Radio frequency signals synthesised from independent
cryogenic sapphire oscillators", Harnett et al., 2014

-- 
The driving force behind research is the question: "Why?"
There are things we don't understand and things we always 
wonder about. And that's why we do research.
		-- Kobayashi Makoto