By nudging a thorium-229 nucleus into a higher energy state, physicists have taken a significant step towards developing a nuclear clock, offering a potential avenue to explore fundamental forces in physics. However, despite this breakthrough, there’s still a considerable journey ahead.
A swirling blue atom symbolizes scientific advancement Researchers have unlocked the key to converting a thorium atom into a nuclear clock, a groundbreaking feat that promises to revolutionize our understanding of the cosmos. This milestone achievement marks the first instance where laser light has been utilized to elevate the nucleus of a thorium atom to a higher energy level, laying the groundwork for a novel clock that not only boasts enhanced precision but also delves into the deepest mysteries of the universe.
The findings, detailed in a paper published on April 29 in Physical Review Letters, underscore the transformative potential of nuclear clocks in timekeeping accuracy and fundamental physics exploration.
Lead researcher Thorsten Schumm, a professor of quantum metrology at the Vienna University of Technology, expressed his elation at witnessing the initial breakthrough, describing it as the culmination of years of meticulous preparation and occasional doubt.
Current timekeeping relies heavily on atomic clocks, which operate by directing lasers at electrons to ascertain their precise energy transitions. However, these clocks have limitations, as the external positioning of electrons renders them susceptible to external disturbances, such as magnetic fields, compromising their accuracy.
In contrast, nuclear clocks harness the energy transitions within atomic nuclei, shielded from external interference. Yet, previous attempts faced challenges due to the considerable energy gaps between nuclear states, posing obstacles for laser-induced transitions.
However, thorium-229 emerged as a promising candidate in the 1970s due to a potentially bridgeable energy gap. Despite its potential, pinpointing this precise energy transition remained a formidable task akin to discerning minute differences in curb heights by dropping balls from skyscrapers.
Over five decades of research, Schumm and his team meticulously narrowed down the energy range required for the transition, eventually trapping an unprecedented number of thorium-229 nuclei inside calcium fluoride crystals to enhance the chances of observing the desired transition. Their perseverance paid off when they finally observed a thorium atom leaping between energy levels, marking an energy change of 8.35574 electron volts.
While achieving parity with atomic clocks in terms of accuracy will necessitate further refinement, this breakthrough offers a tantalizing glimpse into the potential of nuclear clocks to unravel the mysteries of dark energy, dark matter, and fundamental forces shaping our universe.
Schumm emphasized the nuclear clock’s unparalleled ability to measure the energy difference between two bound states of the nucleus, influenced by electromagnetism, the strong nuclear force, and the weak nuclear force. Unlike atomic clocks, which solely rely on electromagnetism, nuclear clocks hold the promise of detecting changes in these fundamental forces over time or space, paving the way for groundbreaking discoveries in physics.
