Final Report Summary - ARENA (Arrays of entangled atoms)
During the course of the project we first demonstrated the trapping of laser-cooled individual atoms in arrays of microscopic dipole traps arranged in planar, arbitrary geometries, such as circles, squares, triangles… The arrays of traps are produced by a single laser beam focused by a large-numerical aperture lens, and is spatially shaped by a computer-controlled reconfigurable spatial-light-modulator. We produced patterns of arbitrary geometry consisting of more than 100 traps, filled randomly with individual atoms.
We then demonstrated excellent control over the interaction between up to 9 individual atoms held in small arrays (lines, triangles). In particular, we measured for the first time the van der Waals 1/R6 interaction between two individual Rydberg atoms as a function of their relative distance R. We used this van der Waals interaction to demonstrate the impossibility to excite more than one atom in the ensemble, a phenomenon called Rydberg blockade. We also observed evidence of entanglement in the ensemble by looking at the scaling of the frequency of the collective excitation with the number of atoms. We then tuned the van der Waals interaction to a resonant regime with a 1/R3 dependence using an electric field and showed an enhanced interaction energy. Finally we demonstrated the dipole-induced energy exchange between 2 Rydberg atoms prepared in two different Rydberg states. By extending this study to a small string of three atoms we benchmarked the quality of the elementary quantum simulator of spin interaction, useful to understand e.g. quantum magnetism or energy transport in biological systems.
The results of this project establish individual Rydberg atoms as a new promising platform for quantum state engineering and quantum simulation.