Comment by soltanov
11 hours ago
Standard atomic clocks probe outer-shell electrons sensitive to stray EM noise; locking directly to the nucleus is how you actually kill environment drift.
11 hours ago
Standard atomic clocks probe outer-shell electrons sensitive to stray EM noise; locking directly to the nucleus is how you actually kill environment drift.
TIL an atomic clock is not a nuclear clock.
the former brings (cesium) atoms, including their electrons, into resonance.
the latter brings (thorium) _nuclei_ into resonance.
both then "just like any clock" measure that oscillation. "simples" ;-)
and I learned "environment" creating drift is temperature, magnetism, anything that influences electrons.
Spot on. Shielding electron transitions from stray thermal and magnetic shifts takes brutal trapping setups. The nucleus provides that isolation for free.
The hope is that with nuclear clocks there will be no need for the very complex single-ion traps or optical lattices required for clocks that use ionic or atomic energy levels.
Even with the atoms of thorium contained in a small crystal, the frequency of their clock transitions should not be influenced by the environment.
Unfortunately, for now no other suitable nucleus has been found, because the frequency corresponding to nuclear energy levels is normally too high for the current or near future technology.
With thorium 229, the potential simplicity of the clock is counterbalanced by the great expense required for producing this artificial isotope.