Laser excitation of Th-229 nucleus: New findings suggest classical quantum physics and nuclear physics can be combined

Amazing stuff! Exciting! 

"... a very specific state of thorium atomic nuclei that promises revolutionary technological applications. It could be used, for example, to build a nuclear clock that could measure time more precisely than the best atomic clocks available today. It could also be used to answer completely new fundamental questions in physics—for example, the question of whether the constants of nature are actually constant or whether they change in space and time. ...
The long-sought thorium transition has been found, and its energy is now known exactly. For the first time, it has been possible to use a laser to transfer an atomic nucleus into a state of higher energy and then precisely track its return to its original state.

This makes it possible to combine two areas of physics that previously had little to do with each other: Classical quantum physics and nuclear physics. A crucial prerequisite for this success was the development of special thorium-containing crystals. ..."

From the abstract:

"The 8.4 eV nuclear isomer state in Th-229 is resonantly excited in Th-doped 

CaF2  crystals using a tabletop tunable laser system. A resonance fluorescence signal is observed in two crystals with different Th-229 dopant concentrations, while it is absent in a control experiment using Th-232. The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum. These results pave the way toward Th-229 nuclear laser spectroscopy and realizing optical nuclear clocks."

Laser excitation of Th-229 nucleus: New findings suggest classical quantum physics and nuclear physics can be combined

Atomic Nucleus Excited with Laser: A Breakthrough after Decades (original news release) The "thorium transition", which physicists have been looking for for decades, has now been excited for the first time with lasers. This paves the way for revolutionary high precision technologies, including nuclear clocks.

Laser Excitation of the Th-229 Nucleus (open access)

FIG. 1. Excitation scheme