Compact and robust repumper light source for 88Sr+ single-ion traps

Optical clocks have accuracies an order of magnitude better than caesium fountain clocks; however, before the second can be re-defined in terms of an optical transition, many different ions and clock configurations must be explored and compared to each other. A clear challenge is then to develop accurate methods to compare clocks. Ideally, transportable optical clocks are needed, and transportability calls for robust light sources.