Portable optical lattice clocks for chronometric levelling and space applications
Abstract
With their supreme accuracy and precision, optical clocks are highly interesting as tools to sense gravity or for precision test of fundamental physics on ground and in space. The first aspect is related to chronometric levelling, where the difference frequency between two clocks measured via e.g. an optical fibre link is related by the relativistic redshift to the potential difference between both clocks. This opens-up a new tool for geodesy that provides high special resolution and avoids accumulation of measurement errors, as in classical levelling. Here, transportable optical clocks will provide the flexibility required by geodesy to choose measurement sites. We will present the evaluation of a transportable strontium-87 lattice clock that is installed in an air-conditioned car trailer for operation in field campaigns. With this clock, we have reached a fractional frequency uncertainty of 2_10^{-17}, which corresponds to a height resolution of 10 cm. This resolution is achieved after 8000 s of averaging. The application of this clock for field campaigns will be discussed.The second apparatus we will discuss originates from the Space Optical Clock consortium, which has the goal to prepare a space mission with a Sr optical lattice clock. The setup is optimized for compactness and low power consumption to provide design guidelines for space-worthy constructions. Presently, the clock is operated with the boson ^{88}Sr. By comparison against PTB's ^{87}Sr laboratory clock, we have measured the isotope shift between ^{88}Sr and ^{87}Sr with an uncertainty of about 12 mHz.This work is supported by DFG (CRC 1128), EU-FP7 (Marie Curie ITN FACT) and the ESA-funded project iSOC.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2030L