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From: John Larkin <jjSNIPlarkin@highNONOlandtechnology.com>
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
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On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> 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 <joegwinn@comcast.net>
>>>> wrote:
>>>> 
>>>>> On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman
>>>>> <jeroen@nospam.please> 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.