Magnetic Microtrap Array of Ultracold Atoms

A novel kind of magnetic microtrap has been demonstrated for ultracold neutral atoms. The microtrap consists of two concentric current loops having radii $r_1$ and $r_2$. A magnetic field minimum can be generated along the axis of the loops with oppositely oriented current flowing through the loops. Selecting $r_2:r_1 = 2.2$ maximizes the microtrap force. The strength and the position of the microtrap can be adjusted by applying an external bias magnetic field. A microtrap array can be formed by aligning individual microtraps together. A linear array of 3 microtraps having $r_1 = 300$ $\mu$m, was loaded with more than 10$^5$ $^{87}$Rb atoms using three different method: 1) from a transported quadrupole magnetic trap, 2) an optical dipole trap, or 3) directly from a spin polarized MOT.