Stuttgart 2012 – wissenschaftliches Programm
Q 34.82: Poster
Dienstag, 13. März 2012, 16:30–19:00, Poster.I+II
Blackbody radiation shift correction of an optical lattice clock from dc Stark shift measurements — •Thomas Middelmann, Stephan Falke, Uwe Sterr, and Christian Lisdat — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig
Good properties for laser cooling and laser trapping often come at the price of a significant sensitivity to blackbody radiation of room temperature environments. For example, optical lattice clocks based on an ultra-narrow transition in 87Sr are nowadays limited in their uncertainty by the uncertainty of the frequency shift induced by the ambient blackbody radiation. As experiments with Cs microwave clocks have shown, measuring the shift induced by a dc electric field may allow to correct the blackbody radiation shift with high accuracy. This is true for our 87Sr clock as well because both clock states are coupled to other states only by transitions that are energetically significantly higher than the peak of the blackbody radiation. Therefore, the blackbody radiation induced shift can be described by the dc Stark shift of its rms electric field to a good approximation.
We apply a dc electric field to the atoms via a specifically designed precision capacitor: Glass plates with a semi-transparent gold layer are optically contacted to gauge blocks. Their separation has been measured interferometrically. With our measurement we will improve the coefficient of the blackbody radiation shift such that its uncertainty only attributes to less than 2· 10−17 to the overall clock uncertainty.
This work is supported by the Centre for Quantum Engineering and Space-Time Research (QUEST) and the ERA-NET Plus Programme.