Ytterbium Thrives as Researchers Celebrate Breakthrough in Science

Researchers from the University of Amsterdam and the University of New South Wales have resolved a long-standing question in atomic physics: whether ytterbium ions (Yb⁺) can occupy unusually long-lived “metastable” states, and how long those states actually persist. Their measurements point to lifetimes that extend for seconds—far longer than typical excited-state behavior.

Ion traps, central to modern quantum technologies, use electromagnetic fields to hold charged atoms in near isolation. The performance of trapped-ion quantum computers and next-generation atomic clocks depends on precise control of which internal energy state an ion occupies. Until now, the detailed lifetimes of certain Yb⁺ metastable states had remained experimentally unclear.

In the experiment, a single Yb⁺ ion was laser-pumped into higher-energy levels. It then decayed through a complex ladder of states, some of which were metastable—meaning they effectively lingered before returning to the ground state. By tracking when fluorescence resumed after the ion was shelved into a dark metastable state, the team directly timed the decay process.

To make the timing measurements reliable, the researchers trapped two ions together. One ion served as the “probe,” continuously fluorescing to reveal the presence and position of its partner. The other ion was prepared in the metastable manifold, cooled, and stabilized without disturbing the state under study, allowing the decay clock to start and stop with high precision.

The resulting decay signals corresponded to lifetimes on the order of about 1 second and 10 seconds. More strikingly, the data also indicated evidence for a metastable state lasting beyond 30 seconds, extending the known window of controllable Yb⁺ behavior.

Zeger Ackerman, the study’s first author, emphasized how the two-ion strategy enabled clean spectroscopy while preventing unwanted perturbations. Complementary atomic-structure calculations then corroborated the experimentally extracted lifetimes and supported the state assignments.

The newly characterized metastable states could become valuable resources in quantum computing schemes and precision metrology. In particular, the researchers highlighted a state with a predicted 1-second lifetime as a promising candidate reachable from the ground state using a single laser pulse.

From a practical standpoint, longer-lived states improve how effectively qubits and related quantum systems can be detected and distinguished. Because Yb⁺ offers rich internal structure, these metastable levels may also support more general quantum information concepts.

Finally, the work provides experimental confirmation of a decades-old theoretical prediction by Fawcett and Wilson, who estimated a 5.2-second lifetime for one specific Yb⁺ metastable state. The measurements landed remarkably close, bringing theory and experiment into alignment.

Keywords

Ion trapping, ytterbium ions, metastable states, quantum computing, atomic clocks, laser spectroscopy, fluorescence detection