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From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Re: OT: Atomic nucleus excited with laser: a breakthrough after
 decades
Date: Wed, 8 May 2024 12:52:27 +0100
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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
>>>>>>    <https://www.sciencedaily.com/releases/2024/04/240429103045.htm>
>>>>>>     The 'thorium transition', which has been sought after for 
>>>>>> decades,
>>>>>>     has now been excited for the first time with lasers.
>>>>>>     This 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.  This 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?

-- 
Martin Brown