Path: ...!Xl.tags.giganews.com!local-1.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Wed, 08 May 2024 17:13:00 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after decades Date: Wed, 08 May 2024 10:11:14 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: <1ccn3jd9ql2fms3jufgolcru50gh83slk1@4ax.com> References: X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 86 X-Trace: sv3-wWx5bEVArjr0Z7YbWvPPi/u+oC98ae/94PZvDk98xzFHAlzvn9GgOlFuRW3mjgsaePPYraGO4SPB1HS!PY9rUXOnAi9/6hBBY2o5UrVGz/MvyV3dLjnRUP8hf6HFSNlkUjK+vpEHTBPBZqdKUgByS7W6fk54!D2+UVQ== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 4850 On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs wrote: >Martin Brown <'''newspam'''@nonad.co.uk> wrote: >> On 08/05/2024 09:44, Jeroen Belleman wrote: >>> On 5/8/24 01:36, John Larkin wrote: >>>> On Tue, 07 May 2024 12:17:24 -0400, Joe Gwinn >>>> wrote: >>>> >>>>> On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman >>>>> wrote: >>>>> >>>>>> On 5/7/24 15:35, Martin Brown wrote: >>>>>>> On 07/05/2024 06:06, Jan Panteltje wrote: >>>>>>>> Atomic nucleus excited with laser: a breakthrough after decades >>>>>>>> ?tps://www.sciencedaily.com/releases/2024/04/240429103045.htm> >>>>>>>> ?e 'thorium transition', which has been sought after for >>>>>>>> decades, >>>>>>>> ?s now been excited for the first time with lasers. >>>>>>>> ?is paves the way for revolutionary high precision technologies, >>>>>>>> including nuclear clocks >>>>>>> >>>>>>> I wonder what the Q value for stimulated nuclear emission is? >>>>>>> >>>>>> >>>>>> They state a centre frequency of roughly 2 PHz and a decay time >>>>>> of 630s, which would put the Q in the 1e19 ballpark. Prodigious. >>>>>> No wonder it was hard to find. >>>>> >>>>> The Time guys have been looking for this forever, so to speak. >>>>> >>>>> It's the only atomic kernel transition with any degree of coupling to >>>>> electromagnetic radiation.? will be orders of magnitude better >>>>> than such as lattice clocks. >>>>> >>>>> There will be a flood of papers. >>>>> >>>>> Joe Gwinn >>>> >>>> They aren't tuning to a resonance, but to the difference between two >>>> close resonances. >>> >>> The current definition of the second uses something similar: Some >>> hyperfine resonance of cesium. Normal resonances are in the optical >>> domain, but hyperfine ones are RF. >> >> Which puts them in the RF frequency domain where counting cycles of the >> continuous sine reference waveform is relatively easy. >> >> Likewise for H-maser another favourite local time reference signal. >> >>> In nuclei, normal transitions are in the gamma domain, and >>> hyperfine ones are in the domain of optics. It's just a change >>> of scale, if you will. >> >> Although there will be some big practical difficulties counting cycles >> of a waveform at 8eV which is up into the UV. What is the current >> highest frequency that a semiconductor divider is capable of accepting? >> >> I know that there are some optical logic circuits about but how capable >> are they at near UV light? >> >> You can't mix this thing down without losing its fidelity. I know how to >> double optical frequencies but how do you halve or quarter them? >> > >You mix with an optical frequency comb, possibly with an intermediate >locking step. > >The cleverest part of the Hall-Haensch comb generator is that you can lock >the blue end of the comb to the second harmonic of the red end, one tooth >off, and lock the difference to a good reference. Then all the teeth have >the same phase noise as the reference oscillator, rather than 20 log(600 >THz / 100 MHz) ~ 138 dB worse, as it would be in a multiplier. > >That 0.002 Hz line width is going to make the locker design entertaining. > >Cheers > >Phil Hobbs Is there any way to divide a lightwave down into the electronic frequency domain? Rubidium clocks use an indirect way that doesn't actually divide.