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

[Jan Panteltje]

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

[Martin Brown]

Post by Jan Panteltje
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?

[Jeroen Belleman]

Post by Martin Brown

Post by Jan Panteltje
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.

Jeroen Belleman

[Joe Gwinn]

On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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

[John Larkin]

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

[Bill Sloman]

Post by John Larkin

Post by Joe Gwinn

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Probably not. The technique to used to generate very precise laser
wavelengths does seem to be difficult and demanding to work with.

The few people who can do it will have a field day, but they will only
generate a few papers - it takes time to do the work and more time to
write it up.

Post by John Larkin
They aren't tuning to a resonance, but to the difference between two
close resonances.

Nuclear energy levels aren't "resonances" but quantum states, and the
transition between them isn't a "resonance" either, though one can talk
about the kind of resonance that would behave in a similar way.

[Jeroen Belleman]

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

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.

Jeroen Belleman

[Martin Brown]

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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?

[Jeroen Belleman]

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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?

Something involving optical frequency combs might work.

Jeroen Belleman

[John Larkin]

On Wed, 8 May 2024 12:52:27 +0100, Martin Brown

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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?

I don't know if there is a way to divide a lightwave-sorts of
frequency down into the electronic domain. Much less gamma ray
frequencies.

Even the small differences cited here are still optical.

[Phil Hobbs]

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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

[Joe Gwinn]

On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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.

Yes, it will be combs and etalons.

I'm waiting for a flood on the Time Nuts reflector.

Joe Gwinn

[Gerhard Hoffmann]

Post by Joe Gwinn

Post by Phil Hobbs
That 0.002 Hz line width is going to make the locker design entertaining.

Yes, it will be combs and etalons.
I'm waiting for a flood on the Time Nuts reflector.
Joe Gwinn

I have posted already a pointer to this thread here on time nuts.

:-) Gerhard dk4xp

[John Larkin]

On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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.

[Jeroen Belleman]

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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

[Phil Hobbs]

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by Martin Brown

Post by Jeroen Belleman

Post by John Larkin

Post by Joe Gwinn
On Tue, 7 May 2024 16:26:27 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Martin Brown

Post by Jan Panteltje
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.

Post by Jeroen Belleman
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.

Not really. There are optical parametric oscillators, but their phase noise
is horrible by comparison. A 1-cm-long crystal produces a nice tunable
output, but its line width will be c/1cm wide.

Degenerate OPOs exist, whose signal and idler are at the same frequency,
but I believe their phase noise is not that different—there’s an additional
degree of freedom in the signal/idler relationship that would have to be
constrained somehow.

Cheers

Phil Hobbs

[Joe Gwinn]

On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
<***@electrooptical.net> wrote:

[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?

Thanks,

Joe Gwinn

[Phil Hobbs]

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?
Thanks,
Joe Gwinn

Don’t have the reference handy, but the basic idea is to use a modelocked
system Ti:sapphire laser at 750 nm to generate ~100-fs pulses, then use
fiber/grating pulse compression to bring that down to a few femtoseconds,
followed by a holey fiber to broaden the spectrum to more than an octave.

Jan Hall is one of the best instruments guys ever.

Cheers

Phil Hobbs

[Joe Gwinn]

On Wed, 8 May 2024 23:35:19 -0000 (UTC), Phil Hobbs

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?
Thanks,
Joe Gwinn

Don’t have the reference handy, but the basic idea is to use a modelocked
system Ti:sapphire laser at 750 nm to generate ~100-fs pulses, then use
fiber/grating pulse compression to bring that down to a few femtoseconds,
followed by a holey fiber to broaden the spectrum to more than an octave.
Jan Hall is one of the best instruments guys ever.

I'll poke around his publications. He's bound to have left tracks.

Thanks,

Joe Gwinn

[Phil Hobbs]

Post by Joe Gwinn
On Wed, 8 May 2024 23:35:19 -0000 (UTC), Phil Hobbs

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?
Thanks,
Joe Gwinn

Don’t have the reference handy, but the basic idea is to use a modelocked
system Ti:sapphire laser at 750 nm to generate ~100-fs pulses, then use
fiber/grating pulse compression to bring that down to a few femtoseconds,
followed by a holey fiber to broaden the spectrum to more than an octave.
Jan Hall is one of the best instruments guys ever.

I'll poke around his publications. He's bound to have left tracks.
Thanks,
Joe Gwinn

His given name is John L.

[Glen Walpert]

Post by Phil Hobbs

Post by Joe Gwinn
On Wed, 8 May 2024 23:35:19 -0000 (UTC), Phil Hobbs

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?
Thanks,
Joe Gwinn

Don’t have the reference handy, but the basic idea is to use a
modelocked system Ti:sapphire laser at 750 nm to generate ~100-fs
pulses, then use fiber/grating pulse compression to bring that down to
a few femtoseconds, followed by a holey fiber to broaden the spectrum
to more than an octave.
Jan Hall is one of the best instruments guys ever.

I'll poke around his publications. He's bound to have left tracks.
Thanks,
Joe Gwinn

His given name is John L.

His Nobel Prize lecture is an interesting read:

https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.78.1279

PDF Free to Read:

https://journals.aps.org/rmp/pdf/10.1103/RevModPhys.78.1279

Nobel Lecture: Defining and measuring optical frequencies*
John L. Hall
Rev. Mod. Phys. 78, 1279 – Published 17 November 2006

*The 2005 Nobel Prize for Physics was shared by Roy J. Glauber, John L.
Hall, and Theodor W. Hänsch. This lecture is the text of Dr. Hall’s
address on the occasion of the award.

[Joe Gwinn]

Post by Joe Gwinn
On Wed, 8 May 2024 23:35:19 -0000 (UTC), Phil Hobbs

Post by Joe Gwinn
On Wed, 8 May 2024 14:45:42 -0000 (UTC), Phil Hobbs
[snip]

Post by Phil Hobbs
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.

Hmm. It had to be true, but I never connected the dots there. What
is mechanism by which this is achieved? References?
Thanks,
Joe Gwinn

Don’t have the reference handy, but the basic idea is to use a modelocked
system Ti:sapphire laser at 750 nm to generate ~100-fs pulses, then use
fiber/grating pulse compression to bring that down to a few femtoseconds,
followed by a holey fiber to broaden the spectrum to more than an octave.
Jan Hall is one of the best instruments guys ever.

I'll poke around his publications. He's bound to have left tracks.

The best source I've found so far is:

Optical and microwave metrology with frequency combs
Tara Fortier
NIST Time and Frequency Division
Oct 10, 2023

And

COMMUNICATIONS PHYSICS | (2019)2:153 |
https://doi.org/10.1038/s42005-019-0249-y | www.nature.com/commsphys

These are open access.

Joe Gwinn

[John Larkin]

On Tue, 7 May 2024 14:35:12 +0100, Martin Brown

Post by Martin Brown

Post by Jan Panteltje
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?

"the correct energy of the thorium transition was hit exactly, the
thorium nuclei delivered a clear signal for the first time. "

I wonder what that signal was.

[Bill Sloman]

Post by John Larkin
On Tue, 7 May 2024 14:35:12 +0100, Martin Brown

Post by Martin Brown

Post by Jan Panteltje
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?

"the correct energy of the thorium transition was hit exactly, the
thorium nuclei delivered a clear signal for the first time. "
I wonder what that signal was.

Presumably the thorium nucleus absorbs the photon, then remits it when
it decays back to the ground state, presumably not in the original
direction.

The life-time of the excited state is 630sec when the thorium atoms are
presented in a CaF2 crystal. It you hit the crystal briefly with
precisely the right frequency, then observed a slowly decaying
fluorescent signal at the same wavelength, you'd have a clear enough
signal (though not all that much of it).

In fact they gradually stepped up the exciting beam wavelength from
148.2 to 150.3 nm.,and observed a fluorescence peak at around 148.38 nm.

The observed central wavelength of the nuclear transition amounted to
148.3821(5) nm, equivalent to a transition energy of 8.35574(3) eV,
which was consistent with the 1 σ-uncertainty of the value reported in
radiative-decay experiments but with 800-fold improved precision.

The implication is that their excitation wavelength wasn't all that
precise either and will need to be made even more precise for nuclear
clock work.

I wonder if they could use it to get Doppler shifts from continental drift?

[Jeroen Belleman]

Post by John Larkin
On Tue, 7 May 2024 14:35:12 +0100, Martin Brown

Post by Martin Brown

Post by Jan Panteltje
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?

"the correct energy of the thorium transition was hit exactly, the
thorium nuclei delivered a clear signal for the first time. "
I wonder what that signal was.

It says so in the paper: Fluorescent UV light.

Jeroen Belleman