Optical clocks and ultra-stable optical oscillators for navigation, space science and astronomy

Weak transitions in single cold trapped ions are highly reproducible as optical frequency standards on account of the high quality factors and stabilities achievable. In recent years, the emergence of femtosecond laser combs for relating the optical frequency directly to the Cs standard has pointed to the potential for optical clock operation of these standards. This paper reports on progress in the three integral aspects of optical clock operation, namely the trapped Sr-88(+) ion optical frequency reference, the optical synthesizer and the optical local oscillator technology.