Systematically investigating the polarization gradient cooling in an optical molasses of ultracold cesium atoms

Abstract

We systematically investigate the dependence of the temperature of cold cesium atoms of polarization gradient cooling (PGC) in optical molasses on experimental parameters, which contain changing modes of cooling laser, PGC interaction time, cooling laser frequency and its intensity. The ′SR′ mode of cooling laser, that means the cooling laser frequency is changed with step mode and cooling laser intensity is changed with ramp mode, is found to be the best for PGC comparing with other ′SS′, ′RS′, and ′RR′ modes. We introduce a statistical explanation and an exponential decay function to explain the variation of cold atomic temperature on time. The heating effect is observed when the cooling laser intensity is lower than the saturation intensity of cold atoms. After optimization, the lowest temperature of cold cesium atoms is observed to be about 4µK with the number of 2×10 9 , the density of 1×10 11 /cm 3 and the phase space density of 4.4×10 -5 . The optimization process and analysis of controllable experimental parameters are also meaningful for other cold atomic systems.

Towards a juggling 87Rb atomic dual fountain

“…Consistent with the conclusion of Ref. 23, finally we got the lowest fountain temperature under the 2 ms step-ramp (SR) mode PGC progress, which means that the cooling laser frequency is stepped to the setting value while its intensity is ramped down during the PGC process. After obtaining the optimal fountain signal (Fig.…”

Experimental study of the dependences of retrieval efficiencies on time delay between magneto-optical-trap being turned off and optical storage

“…So, the required average trial number N for achieving a successful quantum memory event should be proportional to 1/pη. In the case where the storage medium is a cloud of cold atoms, [21][22][23] one needs to first load atoms into MOT and then start a time sequence for operating the storage trials. Loading atoms requires an MOTon period τ M .…”

A Quasi-1D Potential for Bose Gas Phase Fluctuations*

“…[23−27] Low-dimensional Bose gases are typically produced by trapping the pre-cooled atoms in an elongated magnetic or light potential. [28] After applying an additional cooling mechanism, [29,30] such as evaporation cooling, all atoms occupy the ground state of the system and have the same physical shape as well as confinement potential. The representative method is the atom chip method, [31−34] an integrated device in which both electric and magnetic fields are used to confine and manipulate cold atoms.…”