Thirty-seven years ago, scientists first managed to move single atoms, opening up the potential to design materials atom by atom to tailor their properties. Today, several methods exist that allow researchers to manipulate individual atoms to endow materials with unique quantum features and deepen our understanding of quantum phenomena. However, current methods are limited to moving atoms across a material’s surface in two dimensions, often requiring slow processes and high-vacuum, ultracold laboratory settings.
Researchers from MIT, Oak Ridge National Laboratory, and other institutions have developed a technique to move tens of thousands of individual atoms within a material in a matter of minutes, all at room temperature. This method employs algorithms to precisely position an electron beam on a material, scanning it to induce atomic movement. “The results show we can deterministically move atoms within a material’s 3D atomic lattice,” said MIT Research Scientist Julian Klein. This new capability allows for the creation of artificial states of matter, offering potential applications in sensing, optical, and magnetic technologies.
Frances Ross, MIT’s TDK Professor in Materials Science and Engineering, likens the technique to a photocopier that can create columns of identical atomic defects. By moving a few atoms to form defects, researchers can repeatedly build three-dimensional atomic arrangements with tunable functions in a more robust system. In a Nature paper released today, the team described using the method to create over 40,000 quantum defects in a crystalline semiconductor.
The approach offers a novel way to study quantum behavior in materials and could eventually lead to advancements in systems using quantum defects, such as quantum computers and dense magnetic memory. Alongside Klein and Ross, the paper includes contributions from researchers at Oak Ridge National Laboratory, Radbound University, University of Chemistry and Technology Prague, King’s College London, and the National Laboratory of the Rockies.
In 1989, IBM researchers famously arranged 35 atoms to spell “IBM” using a scanning tunneling microscope, marking a significant milestone in precise atomic positioning. The process, however, was time-consuming. Since then, new methods such as optical tweezers and oscillating electric fields have allowed atom manipulation in vacuum conditions, yet they remain limited to surfaces or controlled systems. The MIT team demonstrated the ability to rearrange atoms inside materials, enhancing the design of materials for quantum applications.
Using high-performance microscopes at Oak Ridge National Laboratory, the MIT researchers developed a technique employing algorithms to direct an electron beam with picometer precision. The beam moves through the material in a designed oscillating path, redistributing entire columns of atoms to new locations. This approach allowed them to move columns of chromium atoms in a semiconductor, creating vacancies and interstitials that imparted exotic quantum properties to the crystal.
To verify scalability, the researchers generated over 40,000 defects in 40 minutes, arranging atoms in various patterns and distances to produce different quantum mechanical properties. “These defects interact with their neighbors, allowing us to simulate electron interactions within a molecule,” explained Ross.
The researchers attribute their success to the unique electronic structure of chromium within the semiconductor, and they are exploring other crystals for similar applications. The method has benefits over existing techniques, enabling the creation of quantum properties in materials stable outside vacuum conditions. “This approach is scalable to numerous atomic manipulations,” Klein noted, envisioning new physics from artificial structures formed by moving thousands or millions of atoms.
This new method paves the way for a programmable matter class, potentially advancing stable quantum devices. “This allows access to phenomena requiring specific atomic arrangements,” stated Ross, highlighting the potential for studying complex systems.
Original Source: news.mit.edu
