Laser-cooled Rb clocks

The authors present a preliminary measurement of the cold collision shift for ⁸⁷Rb where they found the shift to be more than a factor of 10 smaller than that of a laser-cooled Cs clock. They also discuss calculations for ⁸⁵Rb and demonstrate a juggling fountain. Juggling fountain clocks can achieve higher stability without requiring large improvements in the local oscillator. In this first Cs juggling experiment, the effects of collisions between juggled balls of atoms are studied