Jim,

For state of the art numbers and plots, here's a recent (2020) paper:

"A Review of Contemporary Atomic Frequency Standards",
by Bonnie Schmittberger, David Scherer
https://arxiv.org/abs/2004.09987
https://arxiv.org/pdf/2004.09987.pdf

It also has plots comparing clock stability vs. size and vs. power.
Highly recommended reading.

There is also a power point version with similar content as the paper:

https://www.gps.gov/cgsic/meetings/2019/scherer.pdf

/tvb

On 11/28/2021 2:05 PM, Lux, Jim wrote:

On 11/28/21 8:03 PM, Tom Van Baak wrote:

Awesome, these are a good start.

It's nice to have a figure to put in to reports and presentations. 
(Larry Young, recently retired from JPL who is a GNSS guru, had a hand
drawn graph that he'd update over the years pasted into his notebook)

DSAC is shown as 10 liters (which is about how big it actually is) - I
remember when John Prestage was talking about the 1 liter atomic clock
more than 10 years ago, but that's the size of the physics package on
the bench, and comparing to USOs.  That was before it was "flight ready".

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

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

Hello Jim

Here is a relatively up to date plot that I made for the T&F course we give.
Labels are a bit misaligned courtesy of PowerPoint,
No CSAC, but there is an SDI cold Rb and a UAdelaide CSO.
Slightly different perspective to the Schmittberger et al plots that
Tom B referenced,

Cheers
Michael

On Mon, Nov 29, 2021 at 9:07 AM Lux, Jim jim@luxfamily.com wrote:

Hi Michael,

Thanks for that plot. I think it sumarizes fairly well what typical
devices of today achieves.

There is rubidiums and quarts that go into the 1E-14s, but most do not.
The old plot uses a "span" for the different technologies and that helps
to avoid the "but this device/product" types of issues.

The optical clocks is not really on there, but the modern cold Rb etc.
should be there.

One clearly sees the benefit of CSOs and there should not be to
surprising to see that they are used in other clocks to improve
performance in that range.

I clearly miss out on having CSOs in my arsenal, otherwise that plot
illustrates much of my experience of measuring these devices in my lab.

Cheers,
Magnus

Den 2021-12-02 kl. 07:13, skrev Michael Wouters: