Exploring Gravity with Optical Clocks

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Motivation

What is an optical clock?

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Projects

EU-FP7 project "SOC2"

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Summary

Team SYRTE (Paris)

• Sr clock evaluation by comparison with Cs atomic fountains, reaching an accuracy of 2 10-15 and a frequency stability of 10-15
• Construction of a second generation Sr vacuum system, implementing the deflection of the atomic beam before capture by the blue MOT
• Design, realization and tests of a new vibration insensitive ultra-stable cavity. Vibration sensitivity is below 10-11/(m/s2) along all three axis and frequency stability between 1 and 2 x 10-15 at 1s (WP 1.6).
• Demonstration of a fiber based frequency transfer with frequency noise <10-18 @ 10000 s over a distance of 172 km
• Construction of a semiconductor laser based second generation lattic)

Team PTB (Braunschweig)

• Sr clock physics package optimization II
- Modelling of trap loading dynamics
- Characterization of trap parameters
Investigations of density dependent shifts and broadenings in a 88Sr lattice clock.
• Sr clock laser development
- Setup of 698 nm clock laser and vibration insensitive cavity
- Linewidth measurement by comparison to PTB´s ultrastable 657 nm laser
- Phase-lock of the laser to ultra-stable laser via a femtosecond optical comb generator.

Team HHUD-I (Univ. Düsseldorf)

• Development and characterization of a novel semiconductor laser system at 1156 nm
• Prestabilization of clock laser to a cavity
• Thermal characterization and stabilization of a ULE reference cavity
• Development of a stabilized 350 m optical fiber link joining two laboratories
• Observation and first frequency measurement of clock transition in 171Yb with the semiconductor laser, together with HHUD-II

Team HHUD-II (Univ. Düsseldorf)

• Experimental realization of a precooling MOT (at 399nm) with Yb using an all-diode laser based system (WP 2.1.)
• Experimental realization and characterization of a scheme for direct loading of Yb into a postcooling MOT (at 556nm) (WP 2.1.)
• Loading of Yb into an optical trap (WP 2.1.)
• Setup and initial characterization of a compact dedicated apparatus for the Yb clock
• Development and setup of a high power grating-stabilized diode laser for the magic-wavelength optical lattice for Yb.
• Development, building and optical characterization of a robust setup for a magic-wavelength 3D-optical lattice with bosonic Yb
• Observation of the optical clock transition in fermionic 171Yb in a MOT (together with HHUD-I)

Team LENS (Univ. Firenze)

• realization of a compact, long-term stable source of cooling light for Sr, with output power P> 300 mW
• design of a compact complete cold Sr atom apparatus