Ytterbium's Narrow Lines: New Frequencies for Quantum Clocks express

Original: "Sub-hertz optical transitions in excited Yb$$^+$$"
arXiv:2602.07352 · 2026-02-07 · CC BY 4.0 · 2 min
An ytterbium atom has revealed three new narrow transitions that could help store quantum information for longer.

📄 Showing the "Simple" version — "Advanced" is not ready yet. Add it to favorites to help prioritize it.

The light an atom emits or absorbs is like a fingerprint: each element has its own pattern of lines. In an ytterbium ion (an atom that has lost one electron), researchers have found three new lines that were previously unused. These lines are very narrow, like thin slits in a fence that let you see far and clearly.

The narrowness of the lines comes from the fact that both the upper and lower states live unusually long. Normally, an excited atom quickly sheds its energy, like a ball rolling down a hill. Here, the ball gets stuck on a shelf and can stay there for milliseconds — an eternity by atomic standards. Such long-lived states are handy for storing quantum information: a qubit won't be destroyed by a random jolt.

Ytterbium is a rare-earth metal that shows up in everyday life in screens and lasers. Its ion is a workhorse of quantum technologies.

The scientists measured the absolute frequencies of these transitions with high precision. It's like knowing the exact address of a house so you can return to it without fail. They also measured frequency shifts for different isotopes (atoms with different numbers of neutrons) and the hyperfine structure — tiny splittings of the lines due to the interaction between the electron and the nucleus.

One of the new states turned out to be especially attractive: it can be excited by a laser and lives long because it decays via slow magnetic radiation. This makes it an ideal candidate for a long-lived qubit — a cell of a quantum computer. The new narrow lines will complement the known ones and help build more accurate clocks and search for deviations from the Standard Model of physics.

Original abstract

as written by the authors arXiv:2602.07352

We present the observation of three semi-forbidden transitions in singly-ionized ytterbium from the metastable $$^{2}\mathrm{F}^o_{7/2}$$ state. Owing to the long lifetimes of both the upper and lower states involved, these transitions are narrow and complement those already frequently used in this atom for quantum information and searches for new physics. We report the absolute frequencies of these electric quadrupole transitions, their isotope shifts, hyperfine structure, and measurements of the quadrupole transition moments. We find that the spontaneous lifetimes of these excited states are limited by slow magnetic dipole emission to lower-lying, odd-parity states, the lowest of which is accessible by laser excitation from $${}^2\mathrm{F}_{7/2}^o$$ and is an attractive candidate for hosting a long-lived qubit.

Ytterbium is named after the Swedish village of Ytterby, where a mineral containing this element was found. The same quarry yielded three other elements: yttrium, terbium, and erbium.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterJames Clerk Maxwell
Concepts
ytterbium ion ytterbium excited state erbium rydberg atom systems rydberg atom sensing charge transfer states helium 3 rydberg atom transition frequency