State-selective transport
Our atoms are cooled to 100 µK and then loaded into a laser trap formed by two counter-propagating beams. The atoms are drawn to the points where the light is strongest, lining them up like pearls on a string. By exploiting the sensitivity of our two spin states to different polarizations of the trap, we can move atoms in the two states in opposite directions. In fact, a left-circular polarization forms a trap only for the atomic state "0" (6S1/2, F=4, mf=4), and the right-circular polarization forms a trap for the atomic state "1" (6S1/2, F=3, mf=3). By overlaying both circularities in our trap and controlling the phase between the two, we can transport atoms depending on their spin state.
Fig. 1: Illustration of the state-selective potential allowing a transport of atoms in opposite directions depending on the internal state of the atoms.
