Cold ions in Space
Ferdinand Schmidt‐Kaler, Peter Wolf, Patrick Robert Gill
Abstract
— Accurate optical frequency standards employ single trapped and laser cooled ions, we review recent experiments. Optical frequencies can be measured with fractional uncertainties of only a few parts in 10 demonstrating the most accurate clocks available today. Demonstrated quantum information techniques help to further improve on determining residual systematic errors. Additionally, entanglement is also demonstrated to increase the signal to noise ratio. For generating the entanglement of a large number of ions, novel ions traps are currently developed which will allow for a coherent manipulation of the order of 10 to 50 ions. As one application of this mature technology, we outline a space mission investigating all aspects of gravity in the outer solar system, using an single ion clock as one of the main onboard instruments. We describe the mission and its major scientific goals centered on tests of fundamental physics and exploration of outer solar system objects. It will allow tests of special and general relativity with unprecedented sensitivity and will yield detailed information on the Kuiper belt circumsolar disk.