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 <[email protected]> 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 <[email protected] <javascript:;>> > To: Discussion of precise time and frequency measurement < > [email protected] <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 > > > _______________________________________________ > time-nuts mailing list -- [email protected] <javascript:;> > 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.
