How ytterbium atoms hunt for new forces of nature ⚡ экспресс
Precision spectroscopy of the clock transition $$^1S_0 \leftrightarrow ^3P_2$$ in neutral ytterbium was performed. The discovery of a magic wavelength at 905.4(2) nm enabled recording a spectrum with a width under 100 Hz. Operating the frequency standard sequentially on different isotopes yielded isotopic shifts for four bosonic isotope pairs with hertz-level uncertainty. Combined with data from four other ultra-narrow transitions in Yb and Yb$$^+$$, a King plot was constructed. Crucially, the new shift values rule out explaining the observed nonlinearity of the three-dimensional King plot solely via new physical interactions—a conclusion that previously required extra constraints from neutron scattering and (g-2)$$_e$$ measurements. These results lay the groundwork for effectively applying precision isotopic shifts in King plot analysis and spur further measurements in ytterbium and other elements.
Every atom has its own 'voice'—the frequency of light it emits. For isotopes—atoms with different numbers of neutrons—the voices differ slightly. It's like a choir: if you know the score precisely, the slightest false note reveals external interference. The King plot is a way to compare how harmoniously two notes from different isotopes sing together. This analysis is a powerful spectroscopic test beyond the Standard Model, capable of detecting even dark matter particles.
Working with ytterbium, physicists found a 'magic' wavelength that works like an ideal microphone: it adds no noise and lets you hear the finest details. After measuring four isotope pairs, they constructed a three-dimensional King plot. The curvature, previously taken as a hint of new physics, turned out to be due to inaccurate reference data on nuclei. The measurement precision was so high that if GPS worked on this principle, it would pinpoint coordinates with an error of a fraction of a millimeter. No new force has been found, but the method has been purified—now it's an ultra-reliable detector of the unknown.
🎯 The frequency of atomic transitions in ytterbium has been measured to 18 decimal places. If GPS used such clocks, it would determine your position with millimeter accuracy.