Compact and Scalable Linear Ion Traps

Scalable linear ion traps offer a very good control of ion ensembles and have become the heart of experiments dealing not only with spectroscopy and frequency standards, but also for quantum computation or simulation. Nevertheless, applications such as high-precision spectroscopy are rendered difficult due to systematic effects affecting the frequency transition of the trapped ions. Among the important effects, the AC Stark shift due to the blackbody radiation, the excess micro-motion and the heating rates are all dependent on the quality of the trap. We therefore develop high-precision scalable linear ion traps optimized for spectroscopy of linear ion chains with extremely small systematic frequency shifts.

Our traps are made of Aluminium Nitride (AlN) which offers a very high thermal conductivity. Integrated Pt100 sensors allow for in-situ measurement of the trap temperature even during the trap operation. We use a FEM model refined by measurements made with an infrared camera to estimate precisely the temperature seen by the ions [1].


The traps are composed of a stack of Gold coated chips glued to a carrier board. Each chip is precisely machined using laser-cutting and laser-structuring techniques. A dedicated fabrication process has been developed at the PTB and allows for reaching machining tolerances below 10 µm and 0.10 mrad. Thanks to this high level of requirements, we could measure in our trap residual RF fields leading to micro-motion at the level of 10-19 [2],[3] and heating rates at the level of 10-20/s (calculated for 115In+).

We also bring our expertise in high-performance traps into play through collaborations with the industry. As part of the Opticlock project [4], we contribute to the development of a demonstrator of a commercial optical ion clock, which will be in a first part based on a single-ion. We develop a new and more compact linear ion trap which will be integrated in a compact vacuum chamber, thus allowing later to do multi-ion spectroscopy in a commercial optical clock.

The most important results can be found here.



[1] Doležal et al., Metrologia 52, 842-856, (2015)

[2] Keller et al., arXiv:1712.02335v2 [physics.atom-ph]

[3] Keller et al., arXiv:1803.08248v1 [physics.atom-ph]