Microscopic Magnetic Quadrupole Trap for Neutral Atoms with Extreme Adiabatic Compression

Abstract

A microscopic magnetic quadrupole trap for neutral atoms has been realized with a combination of permanent magnets, coils, and ferromagnetic pole pieces. The attainable magnetic field gradients of $3\times {10}^5\mathrm{G}/\mathrm{cm}$ infer a spatial extension of the ground state much smaller than the wavelength of optical transitions. The field gradient can be varied over a wide range which allows for efficient loading of $4\times {10}^5$ lithium atoms from a shallow potential by adiabatic transport and compression. During compression the observed 275-fold density increase implies a collision rate increase by a factor of 1700.