Fig. 2: Time-domain matter-wave interferometry:

 Matter-wave interferometer (a): Three retro-reflected VUV laser beams realize the standing light waves as pulsed photo-depletion gratings. The antinodes in G⁽¹⁾ prepare a comb of tightly confined positions from where a molecule may emerge. Because of this projective confinement the wave coherence rapidly expands in free flight to cover several nodes and antinodes by the time the second grating fires. Rephasing of the matter-wave behind G⁽²⁾ then leads to de Broglie interference of each molecule with itself and to the formation of a periodic molecular density pattern around the time when G⁽³⁾ is fired. Only molecules whose wave functions are aligned with the nodes of G⁽³⁾ are transmitted to the detector. The coherent rephasing occurs around a characteristic timescale, the n-th multiple of the Talbot time. A typical measurement (b): we toggle between two interferometer modes: a symmetric mode (resonance), where the grating pulse separation times are kept equal and close to nT_T, and an asymmetric mode (off-resonant or reference), where we set an imbalance of up to 200 ns. Imprinted fringes (c): If the molecular beam velocity has a component parallel to x, the fringe pattern effectively has a transverse velocity component and its position relative to the third grating becomes time dependent. A fringe pattern is visible in case the divergence angle α is smaller than the tilt angle γ.