The world keeps time with the ticks of atomic clocks, but a brand new variety of clock under development — a nuclear clock — could revolutionize how we measure time and probe fundamental physics.
A global research team led by scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado Boulder, has demonstrated key elements of a nuclear clock. A nuclear clock is a novel variety of timekeeping device that uses signals from the core, or nucleus, of an atom. The team used a specially designed ultraviolet laser to exactly measure the frequency of an energy jump in thorium nuclei embedded in a solid crystal. In addition they employed an optical frequency comb, which acts like an especially accurate light ruler, to count the variety of ultraviolet wave cycles that create this energy jump. While this laboratory demonstration isn’t a totally developed nuclear clock, it accommodates all of the core technology for one.
Nuclear clocks might be way more accurate than current atomic clocks, which offer official international time and play major roles in technologies similar to GPS, web synchronization, and financial transactions. For most people, this development could ultimately mean much more precise navigation systems (with or without GPS), faster web speeds, more reliable network connections, and safer digital communications.
Beyond on a regular basis technology, nuclear clocks could improve tests of fundamental theories for a way the universe works, potentially resulting in recent discoveries in physics. They might help detect dark matter or confirm if the constants of nature are truly constant, allowing for verification of theories in particle physics without the necessity for large-scale particle accelerator facilities.
Laser Precision in Timekeeping
Atomic clocks measure time by tuning laser light to frequencies that cause electrons to leap between energy levels. Nuclear clocks would utilize energy jumps inside an atom’s tiny central region, generally known as the nucleus, where particles called protons and neutrons cram together. These energy jumps are very similar to flipping a lightweight switch. Shining laser light with the precise amount of energy needed for this jump can flip this nuclear “switch.”
A nuclear clock would have major benefits for clock precision. Compared with the electrons in atomic clocks, the nucleus is way less affected by outside disturbances similar to stray electromagnetic fields. The laser light needed to cause energy jumps in nuclei is way higher in frequency than that required for atomic clocks. This higher frequency — meaning more wave cycles per second — is directly related to a greater variety of “ticks” per second and subsequently results in more precise timekeeping.
But it is vitally hard to create a nuclear clock. To make energy jumps, most atomic nuclei should be hit by coherent X-rays (a high-frequency form of sunshine) with energies much greater than those who will be produced with current technology. So scientists have focused on thorium-229, an atom whose nucleus has a smaller energy jump than another known atom, requiring ultraviolet light (which is lower in energy than X-rays).
In 1976, scientists discovered this thorium energy jump, generally known as a “nuclear transition” in physics language. In 2003, scientists proposed using this transition to create a clock, and so they only directly observed it in 2016. Earlier this 12 months, two different research teams used ultraviolet lasers they created within the lab to flip the nuclear “switch” and measure the wavelength of sunshine needed for it.
In the brand new work, the JILA researchers and their colleagues create all of the essential parts of a clock: the thorium-229 nuclear transition to offer the clock’s “ticks,” a laser to create precise energy jumps between the person quantum states of the nucleus, and a frequency comb for direct measurements of those “ticks.” This effort has achieved a level of precision that’s a million times higher than the previous wavelength-based measurement. As well as, they compared this ultraviolet frequency on to the optical frequency utilized in one among the world’s most accurate atomic clocks, which uses strontium atoms, establishing the primary direct frequency link between a nuclear transition and an atomic clock. This direct frequency link and increase in precision are an important step in developing the nuclear clock and integrating it with existing timekeeping systems.
The research has already yielded unprecedented results, including the power to watch details within the thorium nucleus’s shape that nobody had ever observed before — it’s like seeing individual blades of grass from an airplane.
The team presents its leads to the Sept. 4 issue of the journal Nature as a canopy story.
Toward a Nuclear Future
While this is not yet a functioning nuclear clock, it’s an important step towards creating such a clock that might be each portable and highly stable. The usage of thorium embedded in a solid crystal, combined with the nucleus’s reduced sensitivity to external disturbances, paves the best way for potentially compact and robust timekeeping devices.
“Imagine a wristwatch that would not lose a second even in the event you left it running for billions of years,” said NIST and JILA physicist Jun Ye. “While we’re not quite there yet, this research brings us closer to that level of precision.”
The research team included researchers from JILA, a joint institute of NIST and the University of Colorado Boulder; the Vienna Center for Quantum Science and Technology; and IMRA America, Inc.
