Re: OT: Atomic nucleus excited with laser: a breakthrough after decades

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.