We carried out a 26-day comparison of five simultaneously operated optical clocks and six atomic fountain clocks located at INRIM, LNE-SYRTE, NPL and PTB by using two satellite-based frequency comparison techniques: broadband Two-Way Satellite Time and Frequency Transfer (TWSTFT) and Global Positioning System Precise Point Positioning (GPS PPP). With an enhanced statistical analysis procedure taking into account correlations and gaps in the measurement data, combined overall uncertainties in the range of 1.8 × 10 −16 to 3.5 × 10 −16 for the optical clock comparisons were found. The comparison of the fountain clocks yields results with a maximum relative frequency difference of 6.9 × 10 −16 , and combined overall uncertainties in the range of 4.8 × 10 −16 to 7.7 × 10 −16 .

In the Galileo FOC phase (Full Operational Capability), GMV is the prime contractor for the Time and Geodetic Validation Facility (TGVF), a contract of the European Space Agency (ESA). Within the TGVF, the Time Validation Facility (TVF) is the subsystem in charge of steering Galileo System Time (GST) to UTC, among other duties. The new TVF is operated at GMV headquarters in Madrid, Spain. TVF operations rely on the contribution of five European timing laboratories, located at INRiM, OP, PTB, ROA, and SP. This paper provides a general description of the TVF element and its related activities for the FOC phase, and presents the main results and findings of the TVF operation until now.

Zinc sulfide (ZnS) nanowires with a typical diameter of 100 to 300 nm have been doped with different concentrations of either Mn or Tb using ion implantation. Both systems show very efficient and long living intra-shell luminescence with strong non-exponential decay characteristics in the range of milliseconds. The time behavior of the corresponding luminescence is well described within a modified Förster model, taking into account the lower dimensionality of the nanowires in case of radiationless dipole-dipole energy transfer. The general applicability of this model for energy transfer processes in low dimensional systems will be shown as a function of concentration, temperature, excitation density as well as for measurements on the level of single nanowires.

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We performed a carrier-phase two-way satellite frequency transfer (TWCP) experiment between LNE-SYRTE and PTB for several days in September 2015. Different hardware configurations were analyzed at the LNE-SYRTE earth station and a suitable configuration was identified by placing up-and down-converters indoors. Additionally atomic fountain frequency standards were operated simultaneously at both institutes. This offered a comparison of two reference clocks at LNE-SYRTE and PTB independently by means of TWCP and via the fountain clocks. Even with a very limited and not continuous measurement time of about 8 hours for TWCP measurements, a frequency transfer uncertainty below 2x10 -15 was achieved and the results by the fountain clocks and TWCP agreed well within this uncertainty.