Atom-level control at MIT

The ultimate degree of control for engineering would be the ability to create and manipulate materials at the most basic level, fabricating devices atom by atom with precise control.

Now, scientists at MIT, the University of Vienna, and several other institutions have taken a step in that direction, developing a method that can reposition atoms with a highly focused electron beam and control their exact location and bonding orientation. The finding could ultimately lead to new ways of making quantum computing devices or sensors, and usher in a new age of ‘atomic engineering’ they say.

“We’re using a lot of the tools of nanotechnology,” explained MIT professor of nuclear science and engineering Ju Li, who holds a joint appointment in materials science and engineering. But in the new research, those tools are being used to control processes that are yet an order of magnitude smaller. “The goal is to control one to a few hundred atoms, to control their positions, control their charge state, and control their electronic and nuclear spin states,” he added.

While others have previously manipulated the positions of individual atoms, even creating a neat circle of atoms on a surface, that process involved picking up individual atoms on the needle-like tip of a scanning tunnelling microscope and then dropping them in position, a relatively slow mechanical process. The new process manipulates atoms using a relativistic electron beam in a scanning transmission electron microscope (STEM), so it can be fully electronically controlled by magnetic lenses and requires no mechanical moving parts. That makes the process potentially much faster, and thus could lead to practical applications.

Using electronic controls and artificial intelligence, “we think we can eventually manipulate atoms at microsecond timescales,” Li said. “That’s many orders of magnitude faster than we can manipulate them now with mechanical probes. Also, it should be possible to have many electron beams working simultaneously on the same piece of material.”