NIST is using atomically precise fabrication to make single atom transistors, few-donor/quantum dot devices, and arrayed few-donor devices for analog quantum simulation (AQS). The goal of the AQS experiments is to explore the Hubbard phase space by fabricating atomically engineered materials whose properties, such as magnetic ordering or Mott insulating phase, depend on the detailed parameters of the atomic configurations.
I will introduce the Hydrogen-based scanning probe lithography technique used for deterministic placement of individual dopant atoms and recent advances to realize true atomic perfection. I will describe our work with donor/quantum dot devices for spin manipulation and readout using RF reflectometry.
We have fabricated arrays of few-atom clusters in silicon that form the sites of a Hubbard model array in the strong interaction regime, where we vary the tunnel coupling with atomic precision between nearby dots from a weakly to strongly tunnel coupled regime. We quantify the electron addition energy spectrum through Coulomb blockade and charge stability analysis and demonstrate tuning of the array’s energy spectrum using gates. We map the Hamiltonian parameters to the physical system to tune the charge occupation, the spatial distribution of the eigenstates, localization/delocalization transition, and Hubbard band structure. Numerical simulations of the model reveal charge distributions and magnetic correlations for different parameter sets that are compared to the physical system.