Nolli, Raffaele; (2018) Rubidium 87 Bose Einstein condensate in a driven 1D optical lattice. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The long term aim of the work is to study non-equilibrium and symmetry-breaking phenomena for a Bose-Einstein condensate in time-dependent optical traps. The work presented in this thesis is mostly devoted to the design, construction and testing of the apparatus, in which condensation was successfully achieved. The first part of this thesis describes the design and construction of a hybrid setup for the production of a Bose-Einstein condensate (BEC) of 87 Rb in the |F = 2, m F = +2 > state. The vacuum system is composed of a first chamber, where a low-velocity intense source (LVIS) of atoms is produced to provide a pre-cooled atomic beam to the science chamber, where the magneto-optical trap (MOT) is produced, trapping more than 3 x 10 8 atoms at a temperature of roughly 400 μK. Forced radio- frequency evaporation is performed in a quadrupole magnetic trap and the atoms are transferred to a hybrid far-detuned optical trap in a crossed-beams configuration; evaporation in the optical potential leads to reliable production of a BEC every 50 s, composed of 10^5 atoms at a temperature of 10-30 nK. To ensure fine control on the optical potential depth and high intensity and pointing stability, a stabilisation system has been developed and characterised. The second part of this thesis describes the realisation of a 1D optical lattice, produced by two phase-locked laser beams emitting at 780 nm, with a red detuning of approximately 3.5 GHz, in counter-propagating configuration. Oscillating forces obtained by phase-modulating the optical potential are applied.

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