[time-nuts] 12.6GhZ Yb clock - was Cs tube pics

[Michael Wouters]

Dear Bob,

The error signal (readout is optical, with a laser) you get from tuning the
microwaves from your synthesis chain to the 12.6 GHz hyperfine transition
in Yb is not continuous. There's a measurement sequence of state
preparation etc that means you only get an error measurement every 10 to
100 s. so you need a good flywheel in between.

Cheers
Michael

On Thursday, 3 November 2016, Bob Stewart <bob at evoria.net> wrote:

> Hi Michael,
> I've got a dumb question about the need for a really good flywheel
> oscillator for the 12.6Ghz Yb clock:  What is the signal that is locking
> that oscillator?  Is it a 1PPS, or is it something in the RF domain, such
> as 10MHz or higher?
> I still hope to make a modern version of the old water-hydrogen generator
> from the 40s or whatever it was.  But, my copious free time seems to be
> taken up now that I have the time to do it.
>
> Bob - AE6RV ------------------------------------------------------
> -----------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>
>       From: Michael Wouters <michaeljwouters at gmail.com <javascript:;>>
>  To: Discussion of precise time and frequency measurement <
> time-nuts at febo.com <javascript:;>>
>  Sent: Wednesday, November 2, 2016 3:42 PM
>  Subject: Re: [time-nuts] Cs tube pics
>
> I worked on a trapped ion frequency standard 20 years ago, a 12.6Ghz Yb
> clock. It's still in the lab across from me and looking at it, and the
> electronics, I think it is the sort of thing that a physicist might
> contemplate building in his/her garage but ...
>
> Building it took about 10 man years of concentrated effort so the time you
> would need for a project like this would be the killer, assuming you could
> buy the spectroscopic lasers and UHV equipment you needed at a price that
> didn't require refinancing your mortgage.
>
> One other vital component is the flywheel oscillator you need to take
> advantage of the fabulous stability you now have at hand.We had a cryogenic
> sapphire oscillator for our (microwave) clock.
>
> For an optical clock, you're also going to need a frequency comb to get
> back into the RF domain.
>
> Cheers
> Michael
>
>
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