Fig. 3: Experimental and simulated spatial matter-wave fringes.
The interference is created in a multi-component BEC by a sequence of three light pulses applied after release. a The associated Bragg processes create several spatially displaced, but still largely overlapping wave packets, resulting in an interference pattern in the three output ports of the interferometer corresponding to a transfer of either +1, −1 or 0 effective photon recoils. The fringes are recorded with and without a prior Stern–Gerlach-type spatial separation of the different spinor components. We model the experiment by solving the 2D-Gross-Pitaevskii equation of a BEC interacting with the light fields discussed in Fig. 1. b, c A close-up of one output port is shown with the corresponding line integrals along the red line (bottom) as well as their theoretical counterparts. The experiment displays a lower contrast due to spatially varying Rabi frequencies. The temporal sequence of the three light pulses also leads to an effective phase imprinting. d–i The stripe pattern (left) and contrast for a data slice (right) observed with and without the Stern–Gerlach separator are depicted. Without Stern–Gerlach separation the stripe pattern obtained for the slice along the orange line (d) features a lower contrast than our model (e) which might result from the relative motion of the spinor components. We observe a higher contrast for different magnetic states (f). Indeed, the components mF = ±1 feature a tilt of opposite sign with respect to the component mF = 0 which points to a residual magnetic field with a curvature in agreement with our numerical simulations (g–i).
