Path: ...!news.nobody.at!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Jeroen Belleman Newsgroups: sci.electronics.design Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after decades Date: Wed, 8 May 2024 23:08:35 +0200 Organization: A noiseless patient Spider Lines: 91 Message-ID: References: <1ccn3jd9ql2fms3jufgolcru50gh83slk1@4ax.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Wed, 08 May 2024 23:06:41 +0200 (CEST) Injection-Info: dont-email.me; posting-host="1d207544d71c75e2e2c5698ec86b0842"; logging-data="204097"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX189U579BfxeV+ezlw46fwwi" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Cancel-Lock: sha1:U8etex5P5dazdRfhD+KLlnQjOFE= In-Reply-To: <1ccn3jd9ql2fms3jufgolcru50gh83slk1@4ax.com> Content-Language: en-US Bytes: 5109 On 5/8/24 19:11, John Larkin wrote: > 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? Not to my knowledge. The usual way is down-mixing. The optical frequency comb provides a way to generate an accurately known optical local oscillator, so to speak. Jeroen Belleman