The research focused on the elusive thorium-229 isotope which possesses a unique property among atomic nuclei: two energy states so close together that they can potentially be manipulated using a standard laser. This finding, detailed in a recent "Physical Review Letters" publication, was achieved in collaboration with the National Metrology Institute of Braunschweig.
Laser manipulation in atomic physics is not new; it is extensively used to alter atomic and molecular states for various applications, including quantum computing and precision measurements like atomic clocks. However, traditional methods have not been applicable to atomic nuclei due to their requirement for energy levels significantly higher than what lasers typically provide.
"The atomic nucleus represents a far more stable quantum system for measurements since it is less affected by external disruptions compared to atomic shells," explained Professor Thorsten Schumm, the lead researcher. The thorium-229 transition, with its minute energy gap, presented a unique opportunity. Yet, the challenge has always been the precision required to detect and manipulate this transition. Even a slight deviation in energy calculations could hinder the transition's detection, akin to locating a minute, specific point on a vast landscape.
To overcome these challenges, Schumm's team developed a novel approach using thorium-doped crystals. This method allows for the simultaneous interaction of lasers with an immense number of thorium nuclei embedded within the crystal lattice. "By using a crystal with thorium atoms, we can amplify the interaction effects, making it easier to detect the nuclear state changes with much higher accuracy and in less time," stated Fabian Schaden, a key scientist involved in the crystal development.
Their breakthrough came on November 21, 2023, when they successfully identified and measured the exact energy level needed to induce the thorium state change. This achievement marks the first time a laser has been used to excite an atomic nucleus, providing a robust signal that confirmed the transition.
This accomplishment has significant implications. One immediate application is the potential development of a nuclear-based clock. Such a device would utilize the thorium transition as its timekeeping element, offering a level of precision surpassing current atomic clocks. "The analogy here is that if atomic clocks are like traditional pendulum clocks, our thorium-based approach could be likened to a quantum metronome with far greater accuracy," Schumm elucidated.
Furthermore, this technology could lead to advanced geophysical measurements, potentially aiding in mineral exploration or earthquake prediction by measuring variations in the Earth's gravitational field with unprecedented precision.
The implications extend into fundamental physics as well. The ability to measure variations in natural constants over time or space could open new frontiers in understanding the universe's underlying principles.
"For us, this marks the culmination of years of dedicated research and the beginning of a new chapter in quantum and nuclear physics," Schumm remarked. "The potential applications are vast and we are just scratching the surface of what might be possible with this technology."
As the research community continues to explore these applications, the excitement surrounding this development is palpable. It represents not only a technical achievement but also a methodological innovation that could redefine precision measurements and quantum state manipulation.
Research Report:Laser excitation of the Th-229 nucleus
Related Links
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