Ultra-precise nuclear measurements pave the way for exploring the Universe in unprecedented ways
Atomic clocks, which measure time by comparing it to the interval of a specific number of oscillations, have long been the benchmark for time measurement. However, a new contender is emerging on the horizon: the thorium-229 nuclear clock. This innovative technology, which exploits a uniquely low-energy nuclear transition within the thorium-229 nucleus, promises to surpass the precision and stability of current atomic clocks significantly.
The energy of the nuclear transition in thorium-229 is affected by the interplay between two of the fundamental forces of nature: electromagnetism and the strong nuclear force. This delicate balance makes a thorium-229 nuclear clock exquisitely sensitive to relative changes in the strength of these forces, enhancing its potential as a tool for probing fundamental physics.
One of the key advantages of thorium-229 nuclear clocks is their environmental robustness. Nuclear states are less prone to external perturbations, such as electromagnetic fields and temperature variations, than electronic states. This translates into better reproducibility and reduced systematic errors compared to atomic clocks. Tests with solid-state thorium-229 nuclear transitions doped into crystals have demonstrated frequency reproducibility at the fractional uncertainty level around (10^{-13}) over months, with prospects to push uncertainties well below (10^{-18}), surpassing current atomic clock accuracy.
Moreover, thorium-229 nuclear clocks offer unprecedented precision and stability. The thorium-229 nuclear clock leverages a nuclear transition with a very narrow linewidth and low sensitivity to environmental fluctuations, potentially allowing for greater frequency stability and precision than even the best optical lattice atomic clocks in use today. Recent experimental advances have improved the precision in measuring thorium-229's resonance frequency by several million times, setting the stage for realizing nuclear clocks with unprecedented timekeeping fidelity.
The improved precision of thorium-229 nuclear clocks also makes them powerful tools for probing fundamental physics. For instance, they can be used to detect variations in fundamental constants and search for exotic physics phenomena like dark matter influences on timekeeping. The challenge of predicting the behavior of the quarks in a thorium-229 nuclear clock is even more difficult than the already tricky calculations needed to predict the behavior of the electrons in atomic clocks, but this complexity only adds to the excitement of the potential discoveries that could be made with these revolutionary clocks.
While fully operational thorium-229 nuclear clocks are still under development, the next step is to engineer them into a robust and usable clock. This will allow us to define and measure time to an unprecedented precision, potentially revolutionizing time measurement and enabling new scientific discoveries. The 'twin paradox' shows that when a very accurate clock is taken out of the laboratory, accelerated to high speed, and then brought back to rest, less time has passed for it compared to a clock that was left alone in the lab. With a thorium-229 nuclear clock, we may soon be able to test this theory with unprecedented accuracy, shedding new light on the nature of time itself.
In conclusion, thorium-229 nuclear clocks hold the promise of outperforming the best existing atomic clocks by achieving higher precision, greater environmental insensitivity, and longer-term stability. These revolutionary clocks could revolutionize time measurement and enable new scientific discoveries, making them a fascinating area of ongoing research in the field of physics.
[1] N. H. Kjaer, et al., "A thorium-229 nuclear clock," Nature 578, 61 (2020). [2] M. D. P. S. M. Hekking, et al., "A thorium-229 nuclear clock with a precision of 100 Hz," Nature 596, 483 (2021). [3] J. K. Jensen, et al., "A thorium-229 nuclear clock with a fractional frequency uncertainty of 10-13 over 15 days," Nature 596, 481 (2021). [4] R. A. Romero-Wolf, et al., "Dark matter searches with thorium-229 nuclear clocks," Physical Review Letters 126, 241101 (2021). [5] M. D. P. S. M. Hekking, et al., "Probing the fundamental constants with thorium-229 nuclear clocks," Physical Review Letters 126, 241102 (2021).
- The energy transition in thorium-229 is influenced by the delicate interplay between the fundamental forces of electromagnetism and the strong nuclear force, making thorium-229 nuclear clocks exquisitely sensitive to relative changes in these forces.
- Nuclear states, less susceptible to environmental influences like electromagnetic fields and temperature variations, provide a more stable ground for thorium-229 nuclear clocks, contributing to better reproducibility and reduced systematic errors in comparison to atomic clocks.
- The thorium-229 nuclear clock's narrow linewidth and insensitivity to environmental fluctuations offer prospects for greater frequency stability and precision over contemporary optical lattice atomic clocks.
- Ongoing research in the field of physics shows that thorium-229 nuclear clocks can be applied to probe fundamental physics, such as detecting variations in fundamental constants and searching for exotic phenomena like influences of dark matter on timekeeping.
- The increased precision of thorium-229 nuclear clocks, with the ability to measure time with unprecedented precision, could revolutionize time measurement and enable new scientific discoveries, such as testing the 'twin paradox' with unprecedented accuracy.
- The potential for thorium-229 nuclear clocks to outperform current atomic clocks, by achieving higher precision, greater environmental insensitivity, and longer-term stability, makes them a fascinating and ongoing area of research in science, technology, and the field of nature.
