Temporal, matter-wave-dispersion Talbot effect

We analyze and experimentally demonstrate a new (temporal) Talbot effect, w here a pulsed phase grating is applied to a cloud of cold atoms (Bose-Einst ein condensate). In contrast to the usual (spatial) Talbot effect, our atom s gain kinetic energy when diffracted by that pulsed grating. The energy ga in and the matter-wave-dispersion relation result in an exact:(no paraxial approximation) Talbot effect where the initial wave front is reconstructed at multiples of a "Talbot time" T-T. We demonstrate the Talbot effect by ap plying a second pulsed phase grating after a variable delay. When this seco nd grating is applied at even (odd) multiples of T-T/2, it doubles (cancels ) the effect of the first pulsed grating.