"Writing" with atoms could change the production of materials for quantum devices

An artist's rendering depicts direct recording with ORNL's Synthescope, a new microscopy technique, to continuously insert tin atoms into graphene, opening up the possibility of fabricating materials atom by atom

A new technology for continuously placing individual atoms exactly where they are needed could lead to new materials for devices that meet critical needs in quantum computing and communications that cannot be produced by conventional means, say the scientists who developed it.

A research team from the Department of Energy's Oak Ridge National Laboratory created new improved tool microscopy, which allows you to “write” with atoms, placing them exactly where they are needed to give the material new properties.

“By working at the atomic scale, we are also working at the scale where quantum properties emerge and are conserved naturally,” says Stephen Jesse, a materials scientist who leads the Nanomaterials Characterization Branch at ORNL's Center for Nanophase Materials, or CNMS.

“We aim to use this improved access to quantum behavior as the basis for future devices that rely on unique quantum phenomena such as entanglement to improve computers, create more secure communications and increase the sensitivity of detectors.”

To achieve improved control over atoms, the research team created a tool they call a synthescope, allowing synthesis to be combined with advanced microscopy. Researchers use a scanning transmission electron microscope, or STEM, converted into platform for manipulating materials at the atomic scale.

The synthoscope will allow us to advance in the creation of materials to the level of individual building blocks. This new approach allows researchers to place different atoms in a material in specific places; new atoms and their arrangements can be selected to impart new properties to the material.

“Classical computers use bits that can be either 0 or 1, and calculations are done by toggling those bits,” says Ondrej Dyck of ORNL, a materials scientist involved in the study. “Quantum computers use qubits that can be both 0 and 1 at the same time. In addition, qubits can become entangled when one of them is connected to the state of another. This entangled system of qubits can be used to solve certain problems much faster than classical computers. The challenge is keeping these fragile qubits stable and functioning correctly in the real world.

“One strategy for solving these problems is to build and operate at a scale where quantum mechanics exists more naturally—at the atomic scale. We realized that if we had a microscope that could look at atoms, then we could use that same microscope to move atoms or change materials with atomic precision. We also want to be able to add atoms to the structures we create, so we need a supply of atoms. This idea grew into a platform for atomic-scale synthesis—the synthescope.”

This is important because the ability to create materials atom by atom could be used in many future technological applications in quantum information science and more broadly in microelectronics and catalysis, as well as for greater understanding of materials synthesis processes. This work could facilitate atomic-scale manufacturing, which is notoriously challenging.

“Simply because we can now put atoms wherever we want, we can think about creating arrays of atoms that are precisely placed close enough to each other that they can become entangled and therefore exchange their quantum properties, which is the key to creating quantum devices that are more powerful than conventional ones,” Dyke said.

Such devices could include quantum computers, the proposed next generation of computers that could significantly outperform today's fastest supercomputers; quantum sensors; and quantum communication devices, which require a source of single photons to create a secure quantum communication system.

“We're not just moving atoms back and forth,” Jesse says. “We are showing that we can add different atoms to the material that weren’t there before and place them where we want them.” Currently, there is no technology that allows you to place different elements exactly where you want them and still get the correct connection and structure. With this technology, we will be able to create structures at the atomic level, taking into account their electronic, optical, chemical or structural properties.”

Conceptual drawing shows a heating platform designed to apply atomized material to a sample, turning a scanning transmission electron microscope into a synthesis scope

Scientists affiliated with CNMS, a nanoscience research center and user center of the U.S. Department of Energy's Office of Science, detailed their research and vision over the course of a year in a series of four scientific journal articles, beginning with proof of principle implementation of the synthesis scope. They applied for a patent on the technology.

“With this work, we are reimagining what atomic-scale manufacturing would look like using electron beams,” Dyke said. “Together, these manuscripts describe what we believe will be the direction of nuclear production technology in the near future and the changes in concepts that are needed to advance the field.”

By using an electron beam, or e-beam, to remove and deposit atoms, ORNL scientists were able to perform direct writing at the atomic level.

“The process is surprisingly intuitive,” says ORNL's Andrew Lupini, leader of the STEM group and a member of the research team. “STEM works by passing a high-energy electron beam through a material. The electron beam is focused to a point smaller than the distance between atoms and scans the material, creating an atomic-resolution image. However, STEM are notorious for damaging the very materials they are printed on.”

Scientists realized that they could take advantage of this destructive “bug” and use it as a design feature, deliberately creating holes. They can then place any atom they want into that hole, exactly where they created the defect. By deliberately damaging a material, they create a new material with other useful properties.

A heating platform was developed to apply atomized material to the sample, turning the scanning transmission electron microscope into a synthesis scope

“We're exploring methods to create these defects on demand so we can place them where we need them,” says Jesse. “Because STEM has atomic-scale imaging capabilities, and we work with very thin materials that are only a few atoms thick, we can see every atom. In this way, we manipulate matter at the atomic level in real time. That's the goal and we achieved it.”

To demonstrate the method, the researchers moved an electron beam back and forth across a graphene lattice, creating tiny holes. They inserted tin atoms into these holes and carried out a continuous, atom by atom, direct writing process, populating with tin atoms the same places where carbon atoms had previously been.

“We believe that atomic-scale fusion processes can become commonplace using relatively simple strategies. Combined with automated beam steering and AI-driven analysis and discovery, the synthescope concept provides a window into atomic fusion processes and offers a unique approach to atomic-scale manufacturing,” says Jesse.