The idea of controlling atoms is not new. In late 1980s, scientists in the field of scanning tunneling microscope (STM) started controlling the position of atoms adsorbed on the surface of metal. The famous "IBM" characters, quantum corral, and a short movie, "a boy kicking soccer", are all created by this method. However, there are two limiting factors constraining this technique from being utilized in a broader way: (1) The atomic structure created has to be stabilized at ultra-low temperature (usually at 4 Kelvin, which is -269 °C). This requires a vacuum chamber to keep the system at such low temperature without getting icy frost covering the surface, so it is extremely hard to bring the atomic structure out of the chamber. (2) It uses a metal tip to control (nudge, drag) the atoms, which is rather slow in forming atomic pattern (just imagine the sluggishness when using only one finger to type on a keyboard, or using a stylus to type the keyboard on your smart phone).

To solve these problems, performing atom control at room temperature using electron beam has just emerged. The reason of using electron beam is illustrated in the following diagram.

This field was thrived from controlling dopant atoms in 2D materials, like graphene or transitional metal dichalcogenides. The image generated by electron microscopes are basically the projection of atomic structure along the z axis. Two-dimensional materials facilitates parsing atomic structures from electron microscope images due to the lack of z dimension. In other words, what you see is what you get (WYSIWYG) when looking at one-atom thick materials in electron microscope. 

2D Atomic Engineering consists of three main parts:

1. Synthesizing proper 2D materials: This is the source of 2D materials you can play with.

2. Controlling/creating atomic structures: this is the bottom-up design part for making atomic structures, generally utilizing atomic resolved imaging technique like scanning tunneling microscope (STM), and aberration-corrected scanning transmission electron microscopes (STEM). Another atom-control techniques include optical tweezer and atomic force microscopy.

3. Applications: The significance of a research is based on its potential in real applications. Three fields are directly correlated to Atomic Engineering:

   1. 1. 1. • Single-atom transistors/memory devices. The main application is to sustain the trend of Moore's law in semiconductor industry where classical computer is still irreplaceable. Different degrees of freedom of a single atom can be used for registering the information, like the direction of spin (electron, nuclear), the position of atoms (e.g. when sitting at different distinguishable lattice sites), etc.

            • Quantum emitters. This gets to quantum information and computation regime where the formalism of computation completely changes compared with classical counterparts. Qubits (quantum bits) in quantum computation, quantum repeaters in quantum communication, and quantum sensors are all realized by certain kind of atomic structures or electronic states. Atomic Engineering can provide manufacturing solutions for these quantum related applications.

            • Single-atom catalysis. This part of application goes to chemistry. Single-atom catalysis has become a very active topic as some of them shows superb catalytic activities when compared with traditional bulk catalyst, and the breakdown of matter into individual atoms also increases the utility rate of each atom. There are many applications of single-atom catalysis like CO2 reduction reaction (CRR) for fighting global warming, hydrogen evolution reaction (HER) to produce clean fuel, nitrogen fixation for producing fertilizer, etc.

Pioneers related to Atomic Engineering (Definitely not a complete list. Please contact me just in case I miss you here):

Atom control using electron microscope

The University of Vienna group (an interesting atom manipulation game can be played here)

Oak Ridge National Laboratory group

University of Chinese Academy of Sciences group

UC Berkeley

2D materials doping

University of Chicago group

Sungkyunkwan Univeristy group

Penn State group

MIT group

Detecting Single-atom device

TU Delft

UC Berkeley