Researchers create quantum dots with single-atom precision

Naval Research Laboratory

The team assembled the dots atom-by-atom, using a scanning tunneling microscope (STM), and relied on an atomically precise surface template to define a lattice of allowed atom positions. The team assembled quantum dots consisting of linear chains of N = 6 to 25 indium atoms; the example shown here is a chain of 22 atoms. Stefan Fölsch, a physicist at the PDI who led the team, explained that the ionized indium adatoms form a quantum dot by creating an electrostatic well that confines electrons normally associated with a surface state of the InAs crystal. Credit: Stefan Fölsch/PDI Because the indium atoms are strictly confined to the regular lattice of vacancy sites, every quantum dot with N atoms is essentially identical, with no intrinsic variation in size, shape, or position. By combining the invariance of quantum dot molecules with the intrinsic symmetry of the InAs vacancy lattice, the team created degenerate states that are surprisingly resistant to environmental perturbations by defects.

Visit Link