麻豆淫院

Optical clocks are highly precise timekeeping devices that measure time by tracking the oscillations of light, as opposed to microwaves, like conventional atomic clocks. The accuracy of these clocks heavily depends on the ability to identify narrow so-called atomic transitions, which are essentially changes in the energy state of electrons in an ion or atom.

Researchers at University of Delaware, 麻豆淫院ikalisch-Technische Bundesanstalt and the Max Planck Institute for Nuclear 麻豆淫院ics are trying to realize increasingly precise optical clocks based on highly charged ions.

In a paper in 麻豆淫院ical Review Letters, they introduce theory-based calculations and a computational approach that could pave the way toward the development of an ultra-stable optical clock based on Ni¹²⁺, a nickel atom that is missing 12 electrons.

"The goal of our experiment was to conduct high precision spectroscopy on highly charged ions," Malte Wehrheim and Piet O. Schmidt, co-authors of the paper, told 麻豆淫院.

"We decided to work with Ni¹²⁺ because it features a very strongly forbidden transition ideally suited for operation as an optical clock. However, because the transition is so strongly forbidden, first estimates hinted toward a search time of a year to scan the 1-sigma uncertainty range around the previously available transition energy using a simple search technique."

The study by Wehrheim, Schmidt and their colleagues was rooted in the extensive work of theoretical physicists, who performed more accurate calculations of the energy changes associated with a narrow transition between two quantum states of electrons in Ni¹²⁺. The results of these calculations served as a starting point for the team's subsequent experimental efforts.

"We were then able to identify the transition within only a few hours even though its natural linewidth is still only less than a trillionth of the uncertainty range," said Wehrheim.

"The great agreement of the measured resonance with their new way of calculating the transition frequency with unprecedented accuracy is the main result of the study. We heavily relied on a good theoretical estimate to roughly know the position of what basically corresponds to a needle in a haystack."

To optimize their experiment, the researchers used a Ti:Sa (Titanium:Sapphire) laser. This solid-state laser can generate light over a very large frequency range, instead of producing light with one fixed wavelength like many other existing lasers.

"We could exclude larger parts of the haystack at a time by scanning over a broad frequency range before detecting an excitation on the clock transition using a helper transition in Ni¹²⁺," explained Wehrheim.

"This helper transition indicated if the Ni¹²⁺ was still in its ground state, or whether our transition was within the scanned part of the haystack. Afterwards, we conducted a divide and conquer approach to reduce the chunk size to finally identify the position of our needle."

The operation of optical clocks is enabled by a very narrow atomic resonance, or in other words, a highly stable transition in the atoms or ions they are based on. The researchers were able to identify this narrow atomic resonance in Ni¹²⁺, which highlights the potential of this particular ion for the future development of atomic clocks.

"We soon plan to conduct high precision spectroscopy and build an atomic clock based on Ni¹²⁺," said the authors. "The hope is that this clock will outperform other clocks because the extreme electronic properties of the highly charged ion make it insensitive to external perturbations and allow more accurate measurements."

This work could have important implications both for the development of optical clocks and for the study of complex atomic systems. In the future, the approach they employed could also be used to accurately locate the transition energies of other highly charged ions in a short period of time.

"Our theoretical collaborators show a pathway to calculating transition energies with unprecedented accuracy for such a multi-electron system," said Schmidt. "This approach can be applied to other systems as well. We were able to validate the accuracy of the calculations experimentally and demonstrated that the identification of narrow transitions is possible in large uncertainty ranges."

This recent study could soon contribute to the advancement of metrology systems based on highly charged ions. This could in turn help to test fundamental physics theories, while also potentially leading to the detection of new phenomena.

"One main goal for our future work will be to use our system to search for dark matter which is predicted to have a stronger coupling to certain transitions in highly charged ions compared to previously investigated species," added Schmidt.

"Ni¹²⁺ serves as a great testbed for our future experiments and allows us to contribute to the improvement of optical clocks."