The Space Optical Clocks Project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems

摘要

The use of ultra-precise optical clocks in space ("master clocks") will allowfor a range of new applications in the fields of fundamental physics (tests ofEinstein's theory of General Relativity, time and frequency metrology by meansof the comparison of distant terrestrial clocks), geophysics (mapping of thegravitational potential of Earth), and astronomy (providing local oscillatorsfor radio ranging and interferometry in space). Within the ELIPS-3 program ofESA, the "Space Optical Clocks" (SOC) project aims to install and to operate anoptical lattice clock on the ISS towards the end of this decade, as a naturalfollow-on to the ACES mission, improving its performance by at least one orderof magnitude. The payload is planned to include an optical lattice clock, aswell as a frequency comb, a microwave link, and an optical link for comparisonsof the ISS clock with ground clocks located in several countries andcontinents. Undertaking a necessary step towards optical clocks in space, theEU-FP7-SPACE-2010-1 project no. 263500 (SOC2) (2011-2015) aims at two"engineering confidence", accurate transportable lattice optical clockdemonstrators having relative frequency instability below 1\times10^-15 at 1 sintegration time and relative inaccuracy below 5\times10^-17. This goalperformance is about 2 and 1 orders better in instability and inaccuracy,respectively, than today's best transportable clocks. The devices will be basedon trapped neutral ytterbium and strontium atoms. One device will be abreadboard. The two systems will be validated in laboratory environments andtheir performance will be established by comparison with laboratory opticalclocks and primary frequency standards. In this paper we present the projectand the results achieved during the first year.