Increasing the Chemical potential by using a Local Optical Ultra-tight Dipole-Trap (i.C.L.O.U.D)

Abstract

Although the experimental set-ups to get in the temperature regime for Bose-Einstein Condensation have been available for many years, there is an even colder regime where we are eager to do research in. It is in this regime that the temperature times the Boltzmann constant becomes of the order of the chemical potential. In this regime exciting new things can be measured, for example, so-called first and second sound switch their behaviour. In the experiment described in this report we reach this regime not by decreasing temperature, but by increasing the chemical potential by making our trap tighter. Usually, this also means that the temperature goes up, but we suppress this effect by creating a thermal bath in the trap. We succeeded in this by using an existing harmonically shaped magnetic trap with a tight dimple shaped optical dipole trap added in the centre. The fact that this trap is not harmonic changes the physics involved. This report features simulations and an experimental part. It this report it is shown that we have reached the regime where the chemical potential and the temperature become of the same order.