1,721,131 research outputs found
Light and the distribution of time
No full textLight allows to time travel: light from the Universe offers the possibility to look back
to its ancestral epochs, at the very first moments. Nowadays light is also a carrier that allows
time to travel, bringing atomic clocks references with the most advanced precision. The frontier of
timekeeping and time transfer using light paves the way to unprecedented applications in science
and metrology. Light is fundamental in the present effort to redefine the unit of time, to improve
our knowledge of fundamental physics laws, geodesy, radioastronomy. Light could be also a new
mean to investigate dark matter in the known Universe and possibly to detect gravitational waves
Systematic shift uncertainty evaluation of IEN CSF1 primary frequency standard
No full textWe report a preliminary systematic shift uncertainty evaluation of our cesium fountain and of the first comparison with the NIST-F1 clock of the National Institute of Standard and Technology (NIST) with a two way satellite comparison system. The stability of the time scale UTC (IEN), (generated with a commercial Cs beam) is insufficient to allow evaluation of systematic shifts by conventional techniques; therefore, the accuracy evaluation of the fountain was accomplished using mainly fast differential techniques, resulting in an overall uncertainty of 3/spl times/10/sup -15/
IEN Cs Fountain Primary Frequency Standard: Contribution to the International Atomic Time and Blackbody Shift Measurements
No full textIEN-CsF1 primary frequency standard at INRIM accuracy evaluation and TAI calibrations
No full textAbstract. In this paper we present an accuracy evaluation of the primary frequency standard IEN-CsF1 of the Italian 'Istituto Nazionale di Ricerca Metrologica'. In particular, we discuss the major improvements applied to the frequency standard that have allowed us to reach a total uncertainty of 8 × 10-16 in a measurement period of 20 days to 25 days. The full metrological chain that links the IEN-CsF1 fountain to the International Atomic Time scale is described and characterized, with respect to its noise and performances
Blackbody radiation shift of the 133Cs hyperfine transition frequency
No full textWe report the theoretical evaluations of the static scalar polarizability of the 133Cs ground state and of the blackbody radiation shift induced on the transition frequency between the two hyperfine levels with mF=0. This shift is of fundamental importance in the evaluation of the accuracy of the primary frequency standards based on atomic fountains and is employed in the realization of the SI second in the International Atomic Time scale at the level of 1×10−15. Our computed value for the polarizability is α0=(6.600±0.016)×10−39C m2∕V in agreement at the level of 1×10−3 with recent theoretical and experimental values. As regards the blackbody radiation shift we find for the relative hyperfine transition frequency β=(−1.49±0.07)×10−14 at T=300 K in agreement with frequency measurements reported by our group and by Bauch and Schröder [Phys. Rev. Lett. 78, 622 (1997)]. This value is lower by 2×10−15 than that obtained with measurem..
Spectral purity transfer with 5 × 10−17 instability at 1 s using a multibranch Er:fiber frequency comb
Full text linkIn this work we describe the spectral purity transfer between a 1156 nm ultrastable laser and a
1542 nm diode laser by means of an Er:fiber multibranch comb. By using both the master laser
light at 1156 nm and its second-harmonic at 578 nm, together with the 1542 nm slave laser,
we investigate the residual noise between the main comb output, the octave-spanning output,
and a wavelength conversion module including non-linear fibers, second-harmonic generation
crystal and amplifiers. With an ultimate stability of the system at the level of 5E−17 at 1 s
and accuracy of 3E−19, this configuration can sustain spectral transfer at the level required
by the contemporary optical clocks with a simple and robust setup
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