Erlangen 2018 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 71: Precision Measurements and Metrology (Optical Clocks) (joint session Q/A)
Q 71.4: Talk
Friday, March 9, 2018, 11:15–11:30, K 2.013
Characterisation of a Reference Cavity for a Transportable Sr Optical Clock. — •Sofia Herbers, Sebastian Häfner, Uwe Sterr, and Christian Lisdat — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
Ultra-stable high-finesse cavities are used, inter alia, in interrogation lasers of optical clocks, that are employed for relativistic geodesy or test of fundamental physics.
One limiting factor of ultra-stable high-finesse cavities is the Brownian noise of the mirror coatings. This noise is reduced for state-of-the-art cavities by using single-crystalline mirror coatings. Furthermore, the cavity needs to be isolated from environmental conditions like seismic noise or temperature fluctuations that result in a length change of the cavity. Therefore, special mounts have to be employed to decouple the cavity from seismic noise. However, for a transportable cavity, most of these approaches like a soft and loose mounting are not suitable. Thus, other solutions must be found that do not degrade the cavity performance.
Here, we present the characteristics of a transportable 20 cm long reference resonator for a transportable Sr lattice clock heading for a fractional frequency instability of 1 · 10−16 using single-crystalline mirrors with a finesse up to 300 000 as well as a rigid cavity mounting.
This work is supported by QUEST and DFG (CRC 1128 (A03)). We thank Garrett Cole and colleagues from Crystalline Mirror Solutions (CMS) for supplying the crystalline coatings used in this work.