Characterization of laser cooling in a high-magnetic-field atom trap

Abstract

We describe cooling and trapping of both ${}^{85}$Rb and ${}^{87}$Rb in a range of magnetic fields up to 2.6 T. Atoms are injected from a low-field pyramidal magneto-optical trap and recaptured in a high-magnetic-field atom trap. The atoms are cooled and trapped by a six-beam optical molasses via the $5{S}_{1/2}|{m}_{I},{m}_{J}=$ 1/2$\ensuremath{\rangle}$$\ensuremath{\rightarrow}$ $5{P}_{3/2}|{m}_{I},{m}_{J}=$ 3/2$\ensuremath{\rangle}$ transition (${m}_{I}=$ 5/2 for ${}^{85}$Rb and ${m}_{I}=$ 3/2 for ${}^{87}$Rb). We study the trap fluorescence spectra, atom temperatures, density distributions, and lifetimes as a function of magnetic field and detuning parameters. The trap fluorescence spectra are both narrow and asymmetric, as is characteristic for laser cooling of atoms in an external trapping potential. The trap is modeled using a Monte Carlo trajectory simulation technique.