Optical atomic clocks are prime candidates for a future redefinition of the SI second. A team from the Physikalisch‑Technische Bundesanstalt (PTB) and the National Institute of Metrology Thailand (NIMT) now reports in Physical Review Letters on a promising new route: an optical multi‑ion clock based on the isotope ytterbium‑173. The concept aims to combine the exceptional accuracy of single‑ion clocks with the enhanced stability obtained by interrogating several ions at once.
The advance rests on a clock transition in 173Yb+ that connects to an excited state with an unusually long lifetime—key for stable measurements. Such transitions typically require strong laser fields, which can introduce detrimental effects. Thanks to the special nuclear shape and specific properties of 173Yb+, the team led by Tanja Mehlstäubler overcame these limitations and was able to drive the transition simultaneously in multiple ions. The team also performed the first measurement of the clock‑state lifetime.
These results open a path towards an optical ytterbium multi‑ion clock operating on this long lifetime state that unites accuracy and stability. 173Yb+ is likewise an attractive multi‑qubit system for quantum information, as its quantum states can be controlled with high precision and more quantum information can be encoded in parallel. The first lifetime measurement further provides new insights into nuclear structure and enables sensitive tests of nuclear physics, including potential effects beyond the Standard Model.
The work was conducted as part of the Cluster of Excellence QuantumFrontiers and the Collaborative Research Centre DQ-mat, among others.
Original publication
Nuclear Spin Quenching of the 2𝑆1/2→2𝐹7/2 Electric Octupole Transition in 173Yb+
Jialiang Yu, Anand Prakash, Clara Zyskind, Ikbal A. Biswas, Rattakorn Kaewuam, Piyaphat Phoonthong, Tanja E. Mehlstäubler
Phys. Rev. Lett. 136, 023002
DOI: 10.1103/fx1b-5666
