In situ measurements of strongly interacting Lithium system

In this thesis, a stable device for the production of a 6Li2 molecular BEC is presented. Lithium atoms are slowed down by a Zeeman Slower and 10^8 atoms are trapped in a Magneto Optical Trap. Of these, ∼ 10^6 atoms are transferred in a red detuned Dipole Trap and an evaporation stage follows, where molecules are formed by tuning interactions via Feshbach resonances. At the end of the evaporation, a condensate containing ∼ 10^4 molecules is produced. The condensate is thus analyzed using both the standard Time of Flight technique and the in situ technique, where interactions between the condensate and thermal part are taken into account. In this description, two models are discussed: the semi-ideal approximation and the Hartree-Fock model. The difference between the two models is discussed and supported by experimental data. Furthermore, the possibility of implementing a Sub-Doppler cooling system for lithium based on the D1 Gray molasses technique is analyzed and a preliminary realization is discussed

Dual-frequency Doppler-free spectroscopy for compact atomic physics experiments

Vapour-cell spectroscopy is widely used for the frequency stabilisation of diode lasers relative to specific atomic transitions - a technique essential in cold atom and ion trapping experiments. Two laser beams, tuned to different frequencies, can be overlapped on the same spatial path as an aid to compactness; this method also enhances the resulting spectroscopic signal via optical pumping effects, yielding an increase in the sensitivity of spectroscopically-generated laser stabilisation signals. Doppler-free locking features become visible over a frequency range several hundred MHz wider than for standard saturated absorption spectroscopy. Herein we present the measured Doppler-free spectroscopy signals from an atomic vapour cell as a function of both laser frequencies, showing experimental data that covers the full, 2D parameter space associated with dual-frequency spectroscopy. We consider how dual-frequency spectroscopy could be used for enhanced frequency-stabilisation of one laser, or alternatively to frequency-stabilise two lasers simultaneously, and analyse the likely performance of such stabilisation methods based on our experimental results. We discuss the underlying physical mechanism of the technique and show that a simple rate-equation model successfully predicts the key qualitative features of our resultsComment: 12 pages, 5 figure

In situ measurements of strongly interacting Lithium system

In this thesis, a stable device for the production of a 6Li2 molecular BEC is presented. Lithium atoms are slowed down by a Zeeman Slower and 10^8 atoms are trapped in a Magneto Optical Trap. Of these, ∼ 10^6 atoms are transferred in a red detuned Dipole Trap and an evaporation stage follows, where molecules are formed by tuning interactions via Feshbach resonances. At the end of the evaporation, a condensate containing ∼ 10^4 molecules is produced. The condensate is thus analyzed using both the standard Time of Flight technique and the in situ technique, where interactions between the condensate and thermal part are taken into account. In this description, two models are discussed: the semi-ideal approximation and the Hartree-Fock model. The difference between the two models is discussed and supported by experimental data. Furthermore, the possibility of implementing a Sub-Doppler cooling system for lithium based on the D1 Gray molasses technique is analyzed and a preliminary realization is discussed