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Topological Matter

Image credit: E. Edwards, JQI

Topological insulators are an example of topological matter and are one of the hottest topics in condensed matter research because of their dual-personality. They are insulators throughout the bulk of the material but are conductors along the edges. Harnessing the underlying phenomena, known as quantum hall physics, is important for developing new types of electronics and quantum information.

In these materials, topological refers to the energy bands. For instance, insulators and conductors have energy diagrams cannot be deformed into one another without opening or closing gaps. The band structure must fundamentally change to go from insulator to conductor.

The effects of topology can extend beyond geometric classification. Physical states characterized by their topology can survive in the presence of disruptions. Topology offers this protection because it is a kind of global aspect of the system.

Quantum systems are fragile; various quantum effects can be disrupted if the participating particles interact with the outside world. Topology can protect quantum states from these disruptions and thus aid the advent of quantum computation.

Scientists can create this unusual behavior in certain two-dimensional materials--such as a layer of electrons at the interface between two semiconductors-- by employing extremely large magnetic fields. What makes topological insulators special is their ability to exhibit this physics without external magnets.

JQI theorists and experimentalists focus on understanding this unusual system and study different platforms and materials that exhibit topological behavior. Researchers are also working on how to construct a robust quantum computer using exotic particles (like Majorana fermions) that may appear in topological matter.

JQI Theoretical Research Groups:

UMD Physics Condensed Matter Theory Center

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