Figure 4

Number of atoms which are (a) reflected into WG2 along a single port, (b) transmitted in WG1, and (c) lost in the other two ports or trapped in the crossing region, as a function of the lattice height ε for four different propagation velocities. The measurements are taken roughly 20 ms after the atoms first arrived at the crossing and are normalized by the total atom number in the trap. Information on the losses from the trap following the passage through the crossing is reported in (d). The relative difference in the atom number measured before and after the interaction with the lattice is shown. In (c,d) we have highlighted with larger symbols the values which correspond to an equal splitting between the two exit ports in WG1 and WG2. Solid lines are guides for the eyes. (e) For v ~5v _R and larger, the atomic cloud can be split into two equally populated fragments propagating along WG1 and WG2 with best efficiency around 80% (comprehensive of the losses from the trap). Note that, by tuning the lattice height in this regime, the splitter can be also used as a mirror with best efficiency larger than 60% (comprehensive of the losses from the trap).