Speaker
Prof.
Ekkehard Peik
(PTB Braunschweig, Germany)
Description
The techniques of trapping and laser cooling of ions have allowed to
perform laser spectroscopy of forbidden transitions with a resolution of
a few hertz. These systems will be used as optical atomic clocks that
offer higher stability and greater accuracy than the best primary cesium
clocks available today. At PTB we have built an optical clock based on a
single trapped ytterbium ion and have shown that the frequencies
realized in two independent ion traps agree to within a few parts in
10^16 . An interesting question from fundamental physics that can be
investigated with optical clocks of this precision is the search for
possible temporal variations of fundamental constants, based on
comparisons between different transition frequencies over time.
Presently, we can infer an upper limit for the relative change of the
fine structure constant of 4*10^-16 per year. We are also investigating
the concept of a nuclear optical clock that will be based on a
low-energy isomeric state in Th-229. Such a system promises further
advances in accuracy and may open a new field at the borderline between
atomic and nuclear physics.
