OCXO Ensemble As Improved Local Oscillator For Atomic Fountains

In this paper we present a technique to improve the phase noise capabilities of local oscillators for atomic fountains. Specifically, the local oscillator is a combined system composed of two independent BVA oscillators. In this way, the measurement time reduces of a factor of two in comparison to the more usual local oscillator realized by one single BV

Measurement of radiative decay and cold collisions trap losses in laser-cooled Ytterbium

Ytterbium lattice frequency standard is an outstanding optical clock with a demonstrated relative frequency accuracy of 3.4·10-16, presently limited by the uncertainty on the blackbody radiation (BBR), lattice polarizabilities and cold collisions shifts. In particular the BBR shift is looming as a major component in the uncertainty budget of many optical frequency standards. In fact the uncertainty on BBR systematic shift in Ytterbium atoms is due both to experimental and theoretical limits in the knowledge of the atomic system: presently Ytterbium has the largest theoretical uncertainty on the BBR shift. Then, both for atomic physics and metrology, new measurements of the Ytterbium atomic properties are strongly demanded, such as the determination of transition matrix elements, lifetimes, branching ratios, polarizabilities and hyperfine constants. In this work we present a set of new measurements for the radiative decay and for the cold collisions trap losses in laser-cooled Ytterbium atoms. These data are relevant to the blackbody radiation shift evaluation and to the cold collisions shift theor

Tracking DDS for Coherent Optical Links

We report on the design and the realization of a digital architecture based on a tracking direct digital synthesizer (DDS) driven by a Field Programmable Gate Array (FPGA) for the implementation of a coherent optical link for time and frequency dissemination. The realized digital system has been implemented and characterized on a real fiber link on a 47 km metropolitan optical telecommunication network using a Dense Wavelength Division Multiplexing, that is shared with the internet data traffic. We describe the technique, the hardware and the characterization of the link, and we compare the new digital system with the analogic one, that uses common fiber links electronics

Tracking DDS for Coherent Optical Links

We report on the design and the realization of a digital architecture based on a tracking direct digital synthesizer (DDS) driven by a Field Programmable Gate Array (FPGA) for the implementation of a coherent optical link for time and frequency dissemination. The realized digital system has been implemented and characterized on a real fiber link on a 47 km metropolitan optical telecommunication network using a Dense Wavelength Division Multiplexing, that is shared with the internet data traffic. We describe the technique, the hardware and the characterization of the link, and we compare the new digital system with the analogic one, that uses common fiber links electronics