The Newest and Most Precise Watch with Charged Ions

The Newest and Most Precise Watch with Charged Ions
New and Most Precise Clock with Charged Ions - Neutral atoms are controlled by scientists in Adam Kaufman's lab at the University of Colorado Boulder using an optical trap system. Trapped atoms are located in the illuminating green field. Thanks to Adam Kaufman

A newly created clock is made less sensitive to external influences and more sensitive to the nuclear nature of ions. Fractional uncertainties 10-18  or about 30 second in 1 billion years, optical clocks provide the most accurate frequency measurements to date.

To date, all have used neutral or oddly charged atoms, but highly charged ions (YYIs), which lack some or even most of the electrons, have been proposed as a possible substitute. Compared to its neutral or single-charged counterparts, the outermost electron is more tightly bound in a YYD. As a result, the electron is less sensitive to external electromagnetic forces. It also has a greater effect on the nucleus of the ion.

High Charge Ion Clocks

However, LTI-based clocks have had their challenges. For example, LTIs are difficult to cool. The ions must expend a significant amount of energy to reach the millikelvin temperatures required for one hour at the megakelvin conditions required to produce such high ionization. In addition, direct laser cooling of YYi is difficult due to the fact that the allowed transitions occur outside the optical wavelengths. Recently, scientists discovered a workaround called sympathetic cooling, which uses the Coulomb interaction to slow down the surrounding YYi.

Piet Schmidt of Germany's National Metrology Institute and colleagues recently demonstrated the first HCI optical clock based on these developments and others. The argon ion Ar with only five electrons13+ fractional uncertainty of proof-of-concept hours using 2.2 × 10−17 was.

The Ar13+ frequency is a single ytterbium ion. 171Yb+ Calculated based on one hour of use.

Schmidt and his colleagues discovered that the time dilation caused by the small movements of the Ar ion in the ion trap is the main cause of uncertainty in the new clock. Future trap designs should be able to eliminate this problem and the uncertainty that follows.

Researchers have used this system to measure the quantum electrodynamic component of nuclear recoil for the first time in a multi-electron system.

two isotopes,  40Ar13+ and 36Ar13+ The frequency difference between them allowed them to calculate the overall recoil.

The result was almost nine orders of magnitude more accurate than previous measurements of isotope shift and was accurate enough to be meaningfully compared to atomic structure predictions.

Schmidt and colleagues discovered that although the effects of quantum electrodynamics are often overlooked in the literature, theoretical predictions and experimental results only agree when these effects are taken into account.

Other LTIs should also be able to use researchers' methods. In addition to quantum electrodynamics, YYI clock transitions are extremely sensitive to potential changes in the fine structure constant and some candidates for dark matter.

Source: physicstoday – Heather M. Hill

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