A physics student just built the world's smallest Christmas tree

You are looking at the world's smallest Christmas tree. While most people strive to make massive Christmas trees, this TU Delft physics student went to the other extreme end. Using a scanning tunneling microscope, Maura came up with the the idea of making a Christmas tree by removing 51 atoms from a perfect crystal lattice. The tree is exactly 4 nanometers tall, or 4 millionths of a millimeter. The scanning tunneling microscope is a complex device that is capable of scanning individual atoms and even changing their position. Maura uses this microscope to build small structures, literally atom by atom, in order to study their quantum mechanical properties.