31–40 of 229 posts
> If the wavelength of the laser is chosen exactly right ... then maybe a special atomic nucleus could be manipulated with a laser, namely thorium-229. On November 21, 2023, the team was finally successful: the correct energy of the thorium transition was hit exactly, the thorium nuclei delivered a clear signal for the first time. So what's the wavelength? I felt like the article left me hanging. The answer is: 148.3…
Is there some direct application? Like using the excitation states of different atoms for storing information?
The article directly stated more precise atomic clocks.
Now how the heck do you generate ~148.38nm light with a narrow linewidth? Their approach using four-wave mixing inherently results in short pulses. .. and given that it decays through gamma emission, does this mean we could now build an optically pumped gamma ray laser?
Now how the heck do you generate ~148.38nm light with a narrow linewidth? Their approach using four-wave mixing inherently results in short pulses. .. and given that it decays through gamma emission, does this mean we could now build an optically pumped gamma ray laser?
A "wavelength converter" might be possible.
PS: Are you sure it's gamma emission? That takes more energy than the exciting UV photon.
What does "exciting a nucleus" mean?
It means getting the nucleus to absorb a certain energy above its ground state. Since it is a quantum object, it can only absorb/emit energy in very specific amounts at once (“quanta”). The details of how the nucleus manifests that extra energy are complicated, but you can imagine it as like, picking up a certain vibrational frequency.
Earlier quoted context omitted.
The article directly stated more precise atomic clocks.
Not a physicist, so I am asking out of curiosity and to learn: have the limitations to the precision of current atomic clocks posed any problems?
> If the wavelength of the laser is chosen exactly right ... then maybe a special atomic nucleus could be manipulated with a laser, namely thorium-229. On November 21, 2023, the team was finally successful: the correct energy of the thorium transition was hit exactly, the thorium nuclei delivered a clear signal for the first time. So what's the wavelength? I felt like the article left me hanging. The answer is: 148.3…
What does "exciting a nucleus" mean?
It means getting the nucleus to absorb a certain energy above its ground state. Since it is a quantum object, it can only absorb/emit energy in very specific amounts at once (“quanta”). The details of how the nucleus manifests that extra energy are complicated, but you can imagine it as like, picking up a certain vibrational frequency.
Earlier quoted context omitted.
Thorium-229 has two energy states. A ground state, and an excited isometric state. The laser is used to transition the nucleus from the ground state to the excited isometric state.
And then?
Earlier quoted context omitted.
And then?
And then the nuclei return to the ground state. That process is probabilistic and measured in half-lives. The key point is that the decay back to ground state happens at a very precise rate that is not influenced by effectively anything, and can be measured accurately. Thus, a clock.
> The decay back to ground state happens at a very precise rate that is not influenced by effectively anything
That sounds contradictory to me.