Superlattices under the microscope

One of the most promising paths in the field of quantum simulation consists in studying interacting ultracold atoms in optical lattices, thus realizing the famous Hubbard model mimicking the behavior of interacting electrons in solids. Such an approach is particularly powerful when combined with the technique of quantum gas microscopy, which allows to “see” individual particles and explore microscopic correlations between them.

This new work takes a step further, by demonstrating quantum gas microscopy of fermionic Lithium atoms with an optical superlattice, i.e. an optical lattice with a more complex structure that allows to engineer a larger class of Hubbard models. The superlattice was realized by combining two commensurable optical wavelengths in a design that allows for outstanding control over its properties — or in other words outstanding control over the extended Hubbard parameters.

The study ranges from single particle to few- and many-body effects, demonstrating double-well oscillations with local readout, correlated quantum walks with next-nearest-neighbors coupling, and inversion of the so-called “super-exchange” turning antiferromagnetism (the tendency of neighboring spins to anti-align) to ferromagnetism (neighboring spins align). This work offers numerous prospects in the field of quantum simulation (e.g. exotic models with mixed-dimensionality, lattice gauge theories) and quantum computation with fermionic particles Physical Review Letter