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Mileti, Gaetano

Nom
Mileti, Gaetano
Affiliation principale
Site web
Fonction
Professeur titulaire
Email
gaetano.mileti@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/479
_
0000-0002-9020-3674

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  • Publication
    Métadonnées seulement
    High performance vapour-cell frequency standards
    (: Journal of Physics: Conference Series 723, 2015-10-27)
    Gharavipour, Mohammadreza 
    ;
    Affolderbach, Christoph 
    ;
    Kang, Songbai 
    ;
    Bandi Nagabhushan, Thejesh 
    ;
    Gruet, Florian 
    ;
    Pellaton, Matthieu 
    ;
    Mileti, Gaetano 
    We report our investigations on a compact high-performance rubidium (Rb) vapour-cell clock based on microwave-optical double-resonance (DR). These studies are done in both DR continuous-wave (CW) and Ramsey schemes using the same Physics Package (PP), with the same Rb vapour cell and a magnetron-type cavity with only 45 cm3 external volume. In the CW-DR scheme, we demonstrate a DR signal with a contrast of 26% and a linewidth of 334 Hz; in Ramsey-DR mode Ramsey signals with higher contrast up to 35% and a linewidth of 160 Hz have been demonstrated. Short-term stabilities of 1.4×10^-13 τ^-1/2 and 2.4×10^-13 τ^-1/2 are measured for CW-DR and Ramsey-DR schemes, respectively. In the Ramsey-DR operation, thanks to the separation of light and microwave interactions in time, the light-shift effect has been suppressed which allows improving the long-term clock stability as compared to CW-DR operation. Implementations in miniature atomic clocks are considered.
  • Publication
    Accès libre
    Theoretical study of the Dick effect in a continuously operated Ramsey resonator
    (2001)
    Joyet, Alain 
    ;
    Mileti, Gaetano 
    ;
    Dudle, Gregor
    ;
    Thomann, Pierre 
    It is well established that passive frequency standards operated in pulsed mode may suffer a degradation of their frequency stability due to the frequency (FM) noise of the Local Oscillator (LO). In continuously operated frequency standards, it has been shown that a similar degradation of the frequency stability may arise, depending on the used modulation-demodulation scheme. In this paper, we report a theoretical analysis on the possible degradations of the frequency stability of a continuous fountain due to the LO FM noise. A simple model is developed to evaluate whether or not aliasing persists. This model is based on a continuous frequency control loop of a frequency standard using a Ramsey resonator. From this model, we derive a general formula, valid for all usual modulation-demodulation schemes, for the LO frequency fluctuations due to aliasing in closed loop operation. We demonstrate that in an ideal situation and for all usual modulation waveforms, no aliasing occurs if the half-period of modulation equals the transit time of atoms in the Ramsey resonator. We also deduce that in the same conditions, square-wave phase modulation provides the strongest cancellation of the LO instabilities in closed loop operation. Finally, we show that the “Dick formula” for the specific case of the pulsed fountain can be recovered from the model by a sampling operation.
  • Publication
    Accès libre
    Laser-pumped paraffin-coated cell rubidium frequency standard
    Bandi Nagabhushan, Thejesh 
    ;
    Affolderbach, Christoph 
    ;
    Mileti, Gaetano 
    We have realized and studied a rubidium atomic frequency standard based on a paraffin-coated cell, exhibiting a short-term frequency stability <3 × 10−12 τ−1/2 between τ = 1 and 100 s. Characterization of the wall-coating is performed by measuring the T1and T2 relaxation times. Perturbations of the medium- to long-term clock stability, due to variations in the laser-intensity, laser frequency, the microwave power shift, and the shifts due to temperature variations are measured and analyzed. A method for reducing the intensity light-shift by detuning the laser frequency and the resulting improvement in clock stability is demonstrated. This work is of relevance for further improvements on Rb cell standards using anti-relaxation wall-coating technology.