A new artificial quantum material for future high-efficiency computers

Scientists at Tsinghua University and Institute of Physics, Chinese Academy of Sciences in Beijing, have demonstrated the ability to control the states of matter, thus controlling internal resistance, within multilayered, magnetically doped semiconductors using the quantum anomalous Hall effect.

The quantum anomalous Hall effect (QAH) occurs in some specially designed materials in which electrons can move a millimeter-scale distance without losing their energy. The ability to apply this effect to devices would allow a new revolution in energy efficiency and computation speed.

In a study published in the journal Chinese Physics Letters, researchers say they have fabricated an artificial material that could be used to develop a topological quantum computer using molecular beam epitaxy, a new technique allowing the stacking of single-molecule-thick layers of crystal, and by exploiting the QAH effect.

A quantum computer takes advantage of the ability of subatomic particles to be in multiple states at once, instead of the binary one or zero seen in conventional computers, allowing them to solve certain types of problems much more efficiently. The topological quantum computer would be a step beyond this. Instead of physical particles, they use a specific type of quasiparticle called the anyon to encode the information.Anyons have been found to be highly resistant to errors in both storing and processing information.

"We canrealise QAH multilayers, or a stack of multiple layers of crystal lattices that are experiencing the QAH effect, with several magnetically doped films spaced by insulating cadmium selenide layers. Since we do it by molecular beam epitaxy, it is easy to control the properties of each layer to drive the sample into different states," says Ke He, a professor at Tsinghua University. Cadmium selenide is a molecule consisting of one cadmium atom and one selenium atom used as a semiconductor; a material whose conductive properties researchers can modify by adding impurities.