The Fermi Gas team at LKB recently published an article in the journal Physical Review Letters.
The authors:
- Joris VERSTRATEN
- Kunlun DAI
- Maxime DIXMERIAS
- Bruno PEAUDECERF
- Tim DE JONGH
- Tarik YEFSAH
We report on the imaging of the in situ spatial distribution of deterministically prepared single-atom wave packets as they expand in a plane, finding excellent agreement with the scaling dynamics predicted by the Schrödinger equation. Our measurement provides a direct and quantitative observation of the textbook free expansion of a one-particle Gaussian wave packet, which we believe has no equivalent in the existing literature. Second, we utilize these expanding wave packets as a benchmark to develop a protocol for the controlled projection of a spatially extended wave function from continuous space onto the sites of a deep optical lattice and subsequent single-atom imaging using quantum gas microscopy techniques. By probing the square modulus of the wave function for various lattice ramp-up times, we show how to obtain a near-perfect projection onto lattice sites. Establishing this protocol represents a crucial prerequisite to the realization of a quantum gas microscope for continuum physics. The method demonstrated here for imaging a wave packet whose initial extent greatly exceeds the pinning lattice spacing, is designed to be applicable to the many-body wave function of interacting systems in continuous space, promising a direct access to their microscopic properties, including spatial correlation functions up to high order and large distances.
© Tarik Yefsah
Figure 1: Single-atom imaging of an ultracold 6Li cloud (LKB experiment). The quantum gas microscope is a powerful tool that was originally developed for the study of lattice physics. Our experiment allows us to apply it to probe continuous gases: after preparing the cloud in a given state of matter, the atoms are suddenly frozen in a deep optical lattice and exposed to near-resonant light. In this image, each bright spot (in red) signals the presence of an atom.
© Tarik Yefsah
Figure 2: A single-atom wave packet expanding in continuous space (top row) is imaged by projecting the atomic position onto the sites of an optical lattice. Our technique serves as a CCD camera for wave functions: through repeated measurements of identically prepared wave packets, we obtain histograms of the absolute squared wave function (bottom row).