New Generation of Timepieces With Record-Shattering Precision

A joint research effort has brought the world closer to creating a nuclear clock by precisely exciting scandium-45 with X-ray pulses. This marks a significant leap in timekeeping technology, with the potential for far-reaching implications for science and industry

An international research team including Dr. Olga Kocharovskaya, a leading professor in the Department of Physics and Astronomy at Texas A&M University, has taken an important step toward developing a new generation of atomic clocks with astonishing potential that will impact the basic science and various industries. , from nuclear physics to satellite navigation and telecommunications.

Pioneering research into the nuclear isomer Scandium-45

The work of the team, led by senior physicist Dr. Yuri Shvyd’ko of Argonne National Laboratory, for the first time, resonantly excited the scandium-45 nuclear isomer with the world’s brightest X-ray pulses at the European XFEl (EuXFEL) X-ray laser facility and determined the position of this nuclear resonance with unprecedented accuracy. Their findings are reported in the journal Natureboth online and in the October 19 print edition.

The potential of atomic and nuclear clocks

“Atomic clocks, such as the cesium-133 clock or the strontium-87 clock, rely on oscillations of electrons in a atomthat can oscillate at very reliable frequencies when excited by microwave or optical radiation,” explains Kocharovskaya, principal investigator of the National Science Foundation (NSF) project that initiated and supported this research.

Scandium, an element used in aerospace components and sports equipment, enables an accuracy of one second in 300 billion years, or about a thousand times more accurate than today’s standard atomic clock. The combination of scandium-45 and ultra-bright X-ray pulses brings scientists a decisive step closer to creating the first-ever nuclear clock that could harness the oscillation of the atomic nucleus instead of the electron shell.

An artist’s rendering of the scandium core clock. Scientists used the X-ray pulses from the European XFEL to excite the atomic nucleus of scandium – the kind of processes that can generate a clock signal with an unprecedented accuracy of one second in 300 billion years. Credit: European XFEL/Helmholtz Institute Jena, Tobias Wüstefeld/Ralf Röhlsberger

“For purposes that require such precision, including the study of certain aspects of relativity, gravity and other physical phenomena such as dark matter, the nuclear clock is the ultimate timepiece,” said Dr. Xiwen Zhang, a postdoctoral researcher in the group by Kocharovskaya. who co-authored the article.

Revolutionary precision timekeeping

With their accuracy down to one part in 10,000,000,000,000,000,000, Texas A&M physicist Dr. Grigory V. Rogachev notes that nuclear clocks could usher in a new era of precise timekeeping and enable transformative applications in numerous fields, resulting in a multitude of applications and advances.

“Humanity has been searching for the technology to create the most accurate clocks since the dawn of modern times,” said Rogachev, chief of Texas A&M Physics and Astronomy and member of the Texas A&M Cyclotron Institute.

“Right now, atomic clocks are the best. Dr. Kocharovskaya and her employees are now taking the first step towards a new, groundbreaking technology. Her research opens a new path to use the unique properties of the scandium-45 isotope to create the most accurate clock ever: the nuclear clock. These advances could have exciting applications in extreme metrology, ultra-high spectroscopy and potentially many other areas.”

Advancing quantum optics and the role of collaborative research

Kocharavskaya’s research interests over the past decade have focused on expanding the field of traditional quantum optics – which she describes as dealing with controllable resonant interactions between optical photons and atomic transitions – to the emerging field of nuclear/X-ray quantum optics focused on control. of resonant interaction between x-ray photons and nuclear transitions. In doing so, she identified scandium-45 with its long-lived, first-excited energy state as the superior candidate for both quantum nuclear storage and the nuclear clock. The main question, she says, was whether it was feasible to achieve this state with the available X-ray sources.

Together with Shvyd’ko, who had envisioned the great potential of scandium-45 for super-resolution coherent-forward nuclear spectroscopy, together with the possibility of its resonant excitation by X-rays from an emerging new generation of accelerator-based facilities 30 years ago, Kocharovskaya wrote a proposal to the NSF focused on resonant excitation of a scandium-45 nuclear isomer using X-ray pulses.

“Initially it received mixed reviews, as it was considered a high-risk, high-reward project, but eventually it was funded, allowing us to plan the experiment at EuXFEL,” said Kocharovskaya, a member of the Texas A&M Institute for Quantum Science . and Technology.

Kocharovskaya calls Shvyd’ko not only the leader of the group’s research, but also a source of inspiration for the entire team. From coordinating the efforts of all groups participating in every detail of the project to holding weekly Zoom meetings discussing the many challenges and progress in preparation for the experiment. She says his leadership and hard work provided a tangible example of what it means to make a long-term scientific dream a reality. Furthermore, she notes that the project would not have been successful without the major contributions of their German colleagues: Dr. Ralf Röhlsberger from DESY and the Helmholtz Institute, Jena; Dr. Jörg Evers from the Max Planck Institute for Nuclear Physics, Heidelberg; and Drs. Anders Madsen and Gianlcuca Geloni at EuXFEL, together with the groups they each lead.

Future directions and challenges

“As soon as the resonance was observed within the first few hours of data collection, we all celebrated this success with joy,” she added. “It was rewarding for all of us, but especially for Yuri, who 33 years ago realized the great scientific potential of scandium-45 for super-resolution nuclear spectroscopy and the possibility of boosting this with modern accelerator-based X-ray sources.”

Never one to rest on its laurels, the team is already focused on the next steps and goals, starting with determining the resonant transition energy with even greater accuracy and measuring the exact lifetime of an isomer state. In addition, there is also observation of the coherent forward nuclear scattering and the linewidth of the nuclear transition is measured.

“The next two steps can be achieved in a relatively simple way,” Zhang acknowledged. “Although the third step is extremely challenging, it is absolutely crucial to estimate the expected accuracy and stability of a future nuclear clock. As a group and as a broader research team, we are all looking forward to the challenge.”