Revolutionizing Timekeeping: The Rise of Safer, More Affordable Nuclear Clocks
Table of Contents
The quest for the most precise timekeeping devices has led scientists to explore the realm of nuclear clocks. Unlike their optical atomic counterparts, which rely on electron transitions, nuclear clocks harness the incredibly stable energy transitions within an atom’s nucleus. This inherent stability promises unparalleled accuracy, potentially surpassing all existing timekeeping technologies.
Though, the path to creating a practical nuclear clock has been fraught with challenges. Thorium-229, a key isotope in this technology, is rare, radioactive, and incredibly expensive to obtain in the quantities needed for research and progress. This has significantly hampered progress.
A recent study published in Nature unveils a game-changing advancement. A team of researchers, led by JILA and NIST Fellow Jun Ye of the university of Colorado Boulder, in collaboration with Professor Eric Hudson’s team at UCLA, have developed a method to make nuclear clocks dramatically safer and more affordable. Their innovation centers around the creation of thin films of thorium tetrafluoride (ThF4).
This breakthrough in thin-film technology represents a potential turning point. The approach aligns with the manufacturing processes used for semiconductors and photonic integrated circuits, suggesting a future where nuclear clocks are more accessible and scalable.
“A key advantage of nuclear clocks is their portability, and to fully unleash such an attractive potential, we need to make the systems more compact, less expensive, and more radiation-kind to users,” said Ye.
The High Cost of Precision
JILA, a renowned institution in atomic and optical clock research, has been instrumental in this progress. Ye’s laboratory has made meaningful contributions to optical lattice clocks, setting new benchmarks in precision timekeeping. For this nuclear clock project, the team collaborated with researchers at the University of Vienna, working with radioactive thorium-229 crystals.
“The growth of that crystal is an art in itself, and our collaborators in Vienna spent many years of effort to grow a nice single crystal for this measurement,” explains Chuankun Zhang, a graduate student at JILA and first author of the Nature studies.
Previous methods using thorium-doped crystals demanded significantly more radioactive material, raising substantial safety and cost concerns. Thorium-229, often derived from uranium decay, is exceptionally expensive.
“Thorium-229 by weight is more expensive than some of the custom proteins I’ve worked with in the past,” adds JILA postdoctoral researcher Jake Higgins, “so we had to make this work with as little material as possible.”
The researchers worked closely with CU Boulder’s Environmental Health & Safety department to ensure safe operation throughout the project.
A Novel Approach: Vaporizing Thorium
The team employed physical vapor deposition (PVD) to create the thin films. This process involves heating thorium fluoride until it vaporizes, allowing the atoms to condense onto a substrate, forming a thin, uniform layer approximately 100 nanometers thick. Sapphire and magnesium fluoride were chosen as substrates due to their transparency to the ultraviolet light used to excite the nuclear transitions.
“If we have a substrate very close by, the vaporized thorium fluoride molecules touch the substrate and stick to it, so you get a nice, even thin film,” zhang explains.
This technique drastically reduced the amount of thorium-229 needed, resulting in a product a thousand times less radioactive while maintaining a high density of active thorium nuclei. Collaborating with the JILA Keck Metrology laboratory and JILA instrument maker Kim Hagen, the researchers consistently produced films suitable for laser-based testing of nuclear transitions.
Overcoming New challenges
The transition to thin films introduced a new hurdle. Unlike the ordered environment of a crystal, the thorium atoms in the film were less uniformly positioned. This required innovative approaches to detect and measure the subtle energy transitions crucial for accurate timekeeping. The team successfully overcame this challenge, paving the way for more practical and widely accessible nuclear clocks.
Revolutionizing Timekeeping: Thin Films Power Next-Gen Atomic clocks
A groundbreaking advancement in atomic clock technology promises to revolutionize industries reliant on precise timekeeping,from telecommunications to GPS navigation. Researchers have successfully utilized thin films to create nuclear clocks with unprecedented accuracy, paving the way for smaller, more portable devices.
The key to this innovation lies in the sheer number of atoms involved. ”The general advantage of using clocks in a solid state, as opposed to in a trapped-ion setting, is that the number of atoms is much, much larger,” explains researcher Higgins. “There are orders and orders of magnitude more atoms than one could feasibly have in an ion trap, which helps with your clock stability.”
This significant increase in atom count dramatically improves the clock’s stability, leading to more precise time measurements. the use of thin films also opens the door to miniaturization, potentially shrinking these devices from bulky laboratory equipment to something far more compact.
The implications are vast.”Imagine something you can wear on your wrist,” envisions researcher Ooi. “You can imagine being able to miniaturize everything to that level in the far, far future.” While wristwatch-sized atomic clocks remain a long-term goal, the potential impact on industries requiring precise timing is undeniable.
The research, detailed in a recent Nature article (doi: 10.1038/s41586-024-08256-5), also hints at a potentially even more significant breakthrough. “If we are lucky, it might even tell us about new physics,” adds researcher Doyle.
The challenges in creating these thin films were significant.JILA graduate student Jack Doyle notes, “Wolfgang Pauli was rumored to have said that ‘God invented the bulk and the surface is of the devil,’ but he might as well have said this because the number of factors that are hard to learn about for a particular surface is immense.” Overcoming these challenges required meticulous work and innovative techniques.
The team’s success in creating and characterizing these functional thin films is a testament to their dedication. ”We made the thin film, we characterized it, and it looked pretty good,” explains JILA graduate student Tian Ooi. “It was cool to see that the nuclear decay signal was actually there.”
this advancement represents a significant leap forward in precision timekeeping, promising a future where highly accurate clocks are readily available and integrated into various aspects of daily life and critical infrastructure.
Revolutionizing Timekeeping: Thin Films Power Next-Gen Atomic Clocks
World Today News Senior editor,Sarah Miller,sits down with Dr.Emily Carter, a leading physicist specializing in atomic clock technology, to explore the latest innovation.
Sarah Miller: Dr.Carter, thanks for joining us today. The recent progress of thorium-based thin films for atomic clocks has generated a lot of excitement. Can you shed some light on why this is such a significant breakthrough?
Dr. Emily Carter: Absolutely.For decades,researchers have been striving to build more accurate clocks,and nuclear clocks hold immense potential in that regard. they leverage the incredibly stable energy transitions in atomic nuclei, promising precision far surpassing conventional atomic clocks. Though,the traditional methods using thorium crystals have several limitations,including the high cost and radioactivity associated with handling large amounts of thorium-229.
Sarah Miller: These thin films seem to address those very issues.
Dr. Emily Carter: Precisely. by creating thin films of thorium tetrafluoride, researchers are now able to achieve the same level of accuracy while drastically reducing the amount of thorium-229 required. This dramatically cuts down the cost and radiation exposure involved.
Sarah Miller: How exactly does this thin film technology work?
Dr. Emily Carter: The process, called physical vapor deposition, essentially involves vaporizing the thorium tetrafluoride and allowing it to condense onto a substrate. This creates a thin, uniform layer, only nanometers thick, but still containing a sufficient density of thorium atoms for accurate measurements.
Sarah Miller: So,this thinner material doesn’tcompromise the accuracy of the clock?
Dr. Emily Carter: That’s right. While the arrangement of thorium atoms in a thin film is less ordered than in a crystal, scientists have overcome this challenge by developing new ways to detect and measure the nuclear transitions.
Sarah Miller: What are the broader implications of this advancement? Which Industries could benefit moast?
Dr. Emily Carter: This technology has the potential to revolutionize various sectors.More accurate timekeeping is essential for GPS navigation systems, telecommunications, basic scientific research, and even financial transactions. Imagine more precise financial transactions, more accurate GPS systems, and advancements in scientific research. This could be a game-changer across the board.
Sarah Miller: Dr. Carter, thank you for illuminating this fascinating development. It certainly seems we’re on the cusp of a new era of timekeeping.
Dr. Emily Carter: you’re most welcome. It’s an exciting time to be working in this field!
