This thesis presents the use of optical tweezers in experiments with cold atoms and Bose-Einstein condensate. First, we describe the properties of Bose-Einstein condensates and cooling of atoms with laser and evaporative cooling. We theoretically discuss optical dipole traps and the interference of two Bose-Einstein condensates. Next, we describe the operation of optical tweezers and present the measurement of the frequency of oscillations of atoms in an optical tweezer trap. In the next chapter, we present our experiments. Evaporative cooling in optical tweezers and the transfer of atoms from a static dipole trap to optical tweezers are demonstrated. Experiments of moving and splitting condensates and clouds of cold atoms are presented. Furthermore, we show the interference of two condensates. Finally, we observe a condensate in a box-like potential prepared with optical tweezers. In this set-up, we study the emergence of soliton trains and the response of the condensate to a periodic modulation of the scattering length.
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