A Coherence Microscope Based on the Matter-Wave Talbot Effect

Imaging is crucial for gaining insight into physical systems. In the case of ultracold atoms in optical lattices, quantum gas microscopes have revolutionized the access to quantum many-body systems by detecting and addressing single atoms on single lattice sites. The novel technique of quantum gas magnification uses matter-wave optics to magnify the density distribution before the optical imaging and therefore allows to directly image the Talbot carpet that forms when releasing the atoms from an optical lattice.

We realize this for a BEC of Lithium-7 atoms in a triangular lattice and map out the spatial coherence by analyzing the contrast of successive Talbot copies. The technique should also allow to reconstruct the fluctuating phase profile of individual samples imaged at a Talbot copy. This will realize a coherence microscope with spatially resolved access to phase information, which allows to study domain walls, thermally activated vortex-pairs, or to locally evaluate coherence in inhomogeneous quantum many-body systems.