An energy-resolved atomic scanning probe

Author(s): Gruss, D; Chien, C-C; Barreiro, J; Ventra, MD; Zwolak, M | Abstract: The scanning tunneling microscope is arguably the most versatile instrument for probing the local density of states of material surfaces, molecules, and devices. Despite its versatility, it has a limited range of accessible energies, whereas other spectroscopic techniques typically have a limited spatial resolution. Tunable atomic systems, though, can mimic, for instance, materials and electronics and probe them in ways not easily achievable by traditional techniques, especially for transport phenomena. Here, we fuse atomic and tunneling techniques to demonstrate a method that provides both spatial and energy resolution, as well as expands the accessible energy range to that prevalent in many-body systems. In this hybrid approach, the current supplies a simple, yet quantitative operational definition of a local density of states for both interacting and non-interacting systems as the rate at which particles can be siphoned from the system of interest by a narrow energy band of non-interacting states. Ultra-cold atomic lattices are a natural platform for implementing this concept to visualize the energy and spatial dependence of the atom density in interacting, inhomogeneous lattices, including ones with nontrivial topologies.