Transportable optical clocks: towards gravimetry based on the graviational redshift

A. Görlitz(1), P. Lemonde(2), C. Salomon(3), S. Schiller(1), U. Sterr(4), G. Tino(5) and the SOC team
(1) Univ. Düsseldorf,
(2) SYRTE Paris,
(3) ENS Paris,
(4) PTB Braunschweig,
(5) Univ. Firenze & LENS

The frequency difference between atomic clocks located at different locations in a gravitational field is fundamentally determined by the difference in gravitational potential. With the new generation of atomic clocks now under development, optical atomic clocks, it should be possible to achieve an equivalent height resolution at the 1 cm level. This type of measurement is a local measurement, complementary to the well-established satellite gravimetry approach. A useful implementation would be a reference optical clock on a satellite, to which a network of (transportable) optical clocks on the ground are compared. Transportable optical clocks demonstrators based on ensembles of neutral atoms in an optical lattice are under development within an ESA/DLR-sponsored project, as a first step towards space clocks. The status and perspectives of the project will be presented.