Researcher Mobility Support

Application code: RMS-24-01-10

Guest working organisation: Physikalisch-Technische Bundesanstalt (PTB) – Germany

Employing Organisation: Centro Español de Metrología (CEM) – Spain

CEM researcher gained hands-on experience in the development of optical ion clocks through collaboration with PTB.

The RMS supported CEM’s early-stage development of an optical ion clock using a commercial Calcium-40 ion trap, through collaboration with PTB, coordinator of 23FUN03 HIOC project, which has extensive experience on optical clocks. The RMS researcher gained hands-on experience in optical clocks equipment, uncertainty analysis, heating rate of ion traps, and clock control systems. PTB provided technical guidance, access to its operational systems, and expertise in frequency shift studies, significantly enhancing CEM’s capabilities. The partnership fostered knowledge transfer and laid the foundation for future clock comparisons and collaborations.

Key Achievements:

Through hands-on experience, technical discussions, and access to PTB’s infrastructure, the RMS researcher gained valuable operational knowledge in areas such as ion trapping, resonator design, laser stabilization systems, detection units, and systematic shift mitigation. 

The mobility allowed for a detailed comparative analysis between PTB’s systems, based on Ytterbium and Strontium ions, and CEM’s Calcium-based system. As a result, the researcher identified specific adaptations necessary for CEM, including, for example, shielding strategies against magnetic and thermal influences.

One of the most impactful outcomes was the deep investigation into helical resonators, an area not previously explored in detail at CEM. This work provided key insights into antenna design, signal quality, and trap efficiency. 

Additionally, the stay supported the development of a structured uncertainty evaluation approach aligned with international practices. The researcher reviewed and tailored models for quantifying key shifts and worked on a preliminary uncertainty budget for CEM’s system.

Beyond technical knowledge, the RMS researcher served as an effective link between the two institutions, facilitating technical exchange and aligning system development strategies. The knowledge gained during the mobility will continue to be implemented at CEM, accelerating the development of a robust and traceable optical ion clock and reinforcing long-term collaboration between the two NMIs.