Just a few months ago, a major breakthrough in decades of development was made, and scientists are already realizing its potential: measuring the gap between quantum energy states of thorium nuclei was used to create the first fundamental nuclear clock.
By combining a strontium atomic clock with a crystal containing a thorium nucleus, a team of physicists has successfully demonstrated the key technology that will lead us to the first fully realized and designed nuclear clock. This milestone, which has yet to be achieved, will open up a whole new realm of ultra-precise timekeeping.
“With this first prototype, we have proven that thorium can be used as a stopwatch for ultra-high-precision measurements,” explains physicist Torsten Strumm from the Vienna University of Technology. “All that remains to be done is technical development, without any major obstacles to look forward to.”
An atomic clock relies on the very precise “ticking” of atoms transitioning between energy states under the influence of a laser, determined by the states of electrons orbiting the nucleus in the atomic nucleus. However, this is much more difficult to achieve with the nucleus itself, because changing the energy state of the nucleus requires much more energy than changing the energy state of the electrons.
However, a nuclear clock would be highly preferable as it would be much more stable and accurate than an atomic clock. In turn, the nuclear clock would allow for more precise measurements of the physical universe, with implications for everything from navigation to the search for dark matter.
Earlier this year, the measurement of the energy jump (difference between energy states) in a thorium nucleus was announced. This allowed Strumm and his colleagues to determine the exact energy required to create a change in energy states, the mechanism that makes the nuclear clock tick. The next step was to show that they could make a clock out of these ticks, and that’s what Strumm and his colleagues are doing now.
The clock they are demonstrating is not a full-fledged nuclear clock experiment, but it is a first step in that direction. The strontium clock at JILA at the National Institute of Standards and Technology is driven by infrared light. The team created a small calcium fluoride crystal containing thorium nuclei whose energy states were changed using vacuum ultraviolet light.
To connect the crystal to the atomic clock, the researchers needed to find a way to convert infrared light into ultraviolet light. They did this by creating a frequency comb of infrared waves and passing it through xenon gas, which interacts with the infrared light to emit ultraviolet waves.
The result was a unified frequency comb that could excite the transition of thorium nuclei and synchronize it with the tick-tock of strontium atoms.
The resulting nuclear tick is no more precise than a strontium atomic clock, but researchers say that now that the basic concept has been proven, the real technology is on the horizon and very close to full realization.
“Imagine a wristwatch that never loses a single second even if you leave it running for billions of years. While we’re not quite there yet, this research gets us closer to that level of certainty,” says Jun Ye, a physicist at JILA.
The team ran their experiments multiple times, each time getting results that were consistent with the atomic clock. The next step is to improve it.
“When we first started the transition, we were able to determine the frequency down to a few gigahertz. That was a thousand times better than anything known before. But now we have precision in the kilohertz range – which is again millions of times better,” says Schumm.
“So we expect to surpass the best atomic clocks in 2-3 years.” The study was published on: Nature.
Source: Port Altele
