Just a few months ago, a huge breakthrough was made decades in the making, and scientists are already realizing its potential: measuring the gap between the quantum energy states of the thorium nucleus was used to create the very first rudimentary nuclear clocks.
By combining a strontium atomic clock with a crystal containing thorium nuclei, a group of physicists has successfully demonstrated a key technology that will lead us to the first fully realized and designed nuclear clocks.
This milestone – yet to be passed – will usher in a new the field of ultra-precise timekeeping.
«With the help of this first prototype, we proved: thorium can be used as a chronometer for ultra-precise measurements, — explains physicist Thorsten Strumm from the Vienna University of Technology. — All that remains is to carry out technical refinement, and no further serious obstacles are foreseen.
An atomic clock is a clock that relies on a very precise "tick" atoms as they switch between energy states under the influence of the laser, which is determined by the state of the electrons orbiting the nucleus in the atomic nucleus.
However, this is much more difficult to achieve with the nucleus itself, as it takes much more to change its energy state of energy than for changing the energy state of electrons.
At the same time, it is expected that the nuclear clock will be much more stable and accurate than the atomic one. In turn, the nuclear clock would allow for more precise measurements of the physical universe, which has implications for everything from navigation to the search for dark matter.
Earlier this year, the measurement of the energy jump was announced — differences between energy states — thorium nuclei. This allowed Strumm and his colleagues to determine the exact energy needed to create a change in energy states — the mechanism on which the nuclear clock will tick.
The next step was to demonstrate that they could create a clock based on this ticking, which Strumm and his colleagues did.
The clock he demonstrated is not a full-fledged nuclear clock, but it is a first step in that direction. The strontium clock at JILA at the National Institute of Standards and Technology is powered by infrared light.
The team created a small crystal of calcium fluoride containing thorium nuclei whose energy states are switched by vacuum ultraviolet radiation.
To connect the crystal to the atomic clock, the researchers needed to find a way to convert infrared light into ultraviolet. To do this, they created a frequency comb of infrared waves and let xenon through the gas, which, interacting with infrared light, emits ultraviolet waves.
The result was a combined frequency comb that could excite the transition of thorium nuclei and synchronize it with the ticking of strontium atoms.
The resulting nuclear tick is no more precise than a strontium atomic clock, but now that the basic concept has been demonstrated, real technology is within sight — and is very close to being fully realized, the researchers say.
«Imagine a wristwatch that does not lose a single second even if you leave it running for billions of years. Although we are not there yet, this study brings us closer to that level of precision,'' says physicist Jun Ye of JILA.