A team of researchers from the Massachusetts Institute of Technology (MIT) and the Oak Ridge National Laboratory (ORNL) in the US has found a way to precisely move tens of thousands of atoms within a matter of minutes using an electron beam at room temperature, paving the way for improvements in quantum systems such as detectors and sensors. 

Nearly 40 years ago, researchers at IBM used a scanning tunneling microscope to arrange 35 atoms of the surface of a crystal to spell out IBM. This was the first time humans succeeded in precisely positioning atoms and began the quantum journey for scientists who then engineered specific defects like atom-sized vacancies and surface atoms in crystalline materials. 

Following this, other advances, such as the use of optical tweezers and oscillating electric fields, have been used to trap neutral atoms or ions. However, so far, these advances are limited to either ultra-cold laboratory environments or the movement of atoms in two dimensions. The work done by MIT researchers could revolutionize quantum research and applications, as atoms can now be moved not just in three dimensions but also at room temperature. 

How did they do it? 

Using high-performance microscopes at ORNL, the researchers used a highly sophisticated set of algorithms to direct an electron beam with a precision of a few picometers at the target atom. Following the tight loop to zero in on its target, the beam then sends electrons through the material in a defined oscillating path. 

The motion of the beam pushes entire columns of atoms to new locations, much as we swipe on our smartphones. The electrons help determine where the beam is in the material. 

“The trick is to use very few electrons in the process of getting that information, so the whole process is fast and does not unintentionally damage your crystal,” explained Julian Klein, MIT researcher, who conceived and directed the project. 

In their experiments, the researchers successfully directed the movement of columns of chromium atoms in a semiconductor material 13 nanometers thick. The atom-sized vacancies created in the material when paired with the displaced atom would give the material exotic quantum properties. 

Scalable, futuristic

Interestingly, the research team generated 40,000 quantum defects in the crystal in as little as 40 minutes. In comparison, IBM researchers had taken hours to move those 35 atoms. This demonstrates the approach’s scalability. 

“It’s like a photocopier that can create columns of identical atomic defects,” added Frances Ross, Professor in Materials Science and Engineering at MIT, in a press release.

“It’s especially useful because you can move a few atoms to form defects, and do it again and again to build atomic arrangements in three dimensions that have tunable functions in a system that is more robust because the defects exist beneath the surface.”

However, the researchers are also wary of the role of the semiconductor material they worked with, since chromium has a unique electronic structure. So, they are also working on determining which other materials this approach will work in. 

“Moving atoms within solids enables the creation of quantum properties in materials that are stable in the air outside of vacuum conditions,” explained Klein. “This approach is also scalable to many atomic manipulations, so moving thousands or millions of atoms to create artificial structures would represent completely new physics.”

The technique lays the foundation for programmable matter, which could lead to the development of stable quantum devices in the future.

The research findings were published in the journal Nature.