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.
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.
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.