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Thomann, Pierre

Nom
Thomann, Pierre
Affiliation principale
Fonction
Professeur honoraire
Email
pierre.thomann@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/481

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  • Publication
    Métadonnées seulement
    CONTINUOUS FOUNTAIN CS STANDARD: STABILITY AND ACCURACY ISSUES
    (Middlesex UK: Patrick Gill, 2002)
    Joyet, Alain 
    ;
    Mileti, Gaetano 
    ;
    Thomann, Pierre 
    ;
    Dudle, G.
    We describe a primary fountain frequency standard operating with a continuous beam of laser-cooled Cs atoms. In such a device, aliasing effects, which may degrade the short-term stability in pulsed fountains, are removed and atomic-noise limited stability can be achieved with a state-of-the art, but commercially available, local oscillator. The present experimental short-term stability is measured to be 2.5 · 10-13τ-1/2. Another feature of the continuous fountain is the reduced atomic density and higher beam temperature which reduces the collisional shift of the atomic frequency below the 10-15 level. The light-shift is an undesirable characteristic of the continuous operation. Without a light-trap, a light-shift of the order of 10-12 has been measured. The shift is stable enough not to affect the frequency stability to 104 seconds (2.5 · 10-15). A rotating light-trap has been constructed and tested to bring the light-shift and the corresponding uncertainty to a negligible level. Various contributions to the accuracy are studied.
  • Publication
    Métadonnées seulement
    Pump-probe spectroscopy and velocimetry of cold atoms in a slow beam
    (2001)
    Di Domenico, Gianni 
    ;
    Mileti, Gaetano 
    ;
    Thomann, Pierre 
    In this paper we report on the first purely "pump-probe" nonlinear laser spectroscopy results in a slow atomic beam. We have observed Raman, Rayleigh, and recoil-induced resonances (RIR) in a continuous beam of slow and cold cesium atoms extracted from a two-dimensional (2D) magneto-optical-trap (MOT) with the moving molasses technique. The RIR enabled us to measure the velocity distribution. therefore the average speed (0.6-4 m/s) and temperature (50-500 muK) of the atomic beam. Compared to time of flight, this technique has the advantage of being local, more sensitive in the low-velocity regime (v
  • Publication
    Métadonnées seulement
    Self-aligned extended-cavity diode laser stabilized by the Zeeman effect on the cesium D-2 line
    (2000)
    Lecomte, Steve
    ;
    Fretel, Emmanuel
    ;
    Mileti, Gaetano 
    ;
    Thomann, Pierre 
    An extended-cavity diode laser at 852 nm has been built especially for the purpose of cooling and probing cesium atoms. It is a compact, self-aligned, and continuously tunable laser source having a 100-kHz linewidth and 60-mW output power. The electronic control of the laser frequency by the piezodriven external reflector covers a 4.5-kHz bandwidth, allowing full compensation of acoustic frequency noise without any adverse effect on the laser intensity noise. We locked this laser to Doppler-free resonances on the cesium D-2 line by using the Zeeman modulation technique, resulting in the frequency and the intensity of the laser beam being unmodulated. We also tuned the locked laser frequency over a span of 120 MHz by using the de Zeeman effect to shift the F = 4-F' = 5 reference transition. (C) 2000 Optical Society of America. OCIS codes: 140.2020, 140.3570, 140.3600, 260.7490, 300.6460.
  • Publication
    Métadonnées seulement
    An alternative cold cesium frequency standard: The continuous fountain
    (: Ieee-Inst Electrical Electronics Engineers Inc, 1999)
    Dudle, Gregor
    ;
    Mileti, Gaetano 
    ;
    Joyet, Alain 
    ;
    Fretel, Emmanuel
    ;
    Berthoud, Patrick
    ;
    Thomann, Pierre 
    We report on the primary frequency standard now under construction at the Observatoire de Neuchatel (ON). The design is based on a continuous fountain of laser-cooled cesium atoms, which combines two advantages: the negligible contribution of collisions to the inaccuracy and the absence of stability degradation caused by aliasing effects encountered in pulsed operation. The design is reviewed with special emphasis on the specific features of a continuous fountain, namely the source, the microwave cavity (TE021 mode), and the microwave modulation scheme, The possible sources of frequency biases and their expected contributions to the error budget are discussed. Based on present data, an accuracy in the low 10(-15) range and a short-term stability of 7 . 10(-14) are attainable simultaneously under the same operating conditions.
  • Publication
    Métadonnées seulement
    Bright, slow, and continuous beam of laser-cooled cesium atoms
    (1999)
    Berthoud, Patrick
    ;
    Fretel, Emmanuel
    ;
    Thomann, Pierre 
    By the moving molasses technique we have extracted laser-cooled cesium atoms in a continuous way directly from an optical molasses. The mean launching velocity is precisely tunable from 1 to 12 m/s. The atomic beam has a flux of 1.3 x 10(8) atom/s at 7 m/s and a longitudinal temperature of 70 mu K; which represents the highest flux and lowest velocity spread obtained so far in a continuous beam of cold atoms. These features makes it well suited for atomic fountains. The atomic flux can be slightly increased in a two-dimensional magneto-optical trap operation (+40%). A simple model accounts for the observed dependence of the flux with the magnetic-field gradient. [S1050-2947(99)51212-2].