Abstract
The phenomenon of matter-wave interference lies at the heart of quantum physics. It has been observed in various contexts in the limit of non-interacting particles as a single-particle effect. Here we observe and control matter-wave interference whose evolution is driven by interparticle interactions. In a multi-path matter-wave interferometer, the macroscopic many-body wave function of an interacting atomic Bose–Einstein condensate develops a regular interference pattern, allowing us to detect and directly visualize the effect of interaction-induced phase shifts. We demonstrate control over the phase evolution by inhibiting interaction-induced dephasing and by refocusing a dephased macroscopic matter wave in a spin-echo-type experiment. Our results show that interactions in a many-body system lead to a surprisingly coherent evolution, possibly enabling narrow-band and high-brightness matter-wave interferometers based on atom lasers.
Highlights
Matter wave interference has been observed as a single particle effect for electrons[1], neutrons[2], atoms and molecules[3]
Macroscopic matter wave interference was first directly observed in the case of two independent atomic Bose-Einstein condensates (BEC) that were brought to overlap[4]
We demonstrate a high degree of coherence by reversing the nonlinear phase evolution, thereby refocusing the BEC momentum wave function
Summary
Mattias Gustavsson[1], Elmar Haller[1], Manfred J. In a multi-path matter wave interferometer, the macroscopic many-body wave function of an interacting atomic Bose-Einstein condensate develops a regular interference pattern, allowing us to detect and directly visualize the effect of interactioninduced phase shifts. Macroscopic matter wave interference was first directly observed in the case of two independent atomic Bose-Einstein condensates (BEC) that were brought to overlap[4]. A possible solution is to operate BEC-based interferometers in the non-interacting limit[12,13] by exploiting the cancellation of the scattering phase shift near a scattering resonance. This condition, is difficult or impossible to fulfill for most atomic species. A can be switched to zero to stop the interaction driven part of the evolution in the interferometer or to perform high resolution wave function imaging in momentum space
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