# Quantum Materials

**- Quantum Materials**

Quantum materials is a general term in condensed matter physics, which covers all materials whose fundamental properties cannot be described by semi-classical particles and low-level quantum mechanics.

These materials have strong electronic correlations or some type of electronic order, such as superconducting or magnetic order, or materials whose electronic properties are related to non-universal quantum effects - topological insulators, Dirac electronic systems (such as graphene) As well as systems whose collective properties are governed by true quantum behavior, such as ultracold atoms, cold excitons, polarons, etc.

At the microscopic level, the four fundamental degrees of freedom—charge, spin, orbital, and lattice—interweave to produce complex electronic states; the emerging concept is a common thread in quantum materials research.

Quantum materials exhibit puzzling properties that have no counterparts in the macroscopic world: quantum entanglement, quantum fluctuations, robust boundary states that depend on the material's bulk wavefunction topology, etc. Quantum anomalies such as the chiral magnetic effect link some quantum materials to processes in the high-energy physics of quark-gluon plasmas.

**- Topological Quantum Materials**

Topological materials are a class of materials that have different electrical or optical properties on their surfaces than in their interiors. They have been a focus of research since the discovery of topological insulators, which won the 2016 Nobel Prize in Physics.

Topological materials include:

- Topological insulators: These materials are insulating in bulk and conducting at the surface.
- Semimetals: These materials have valence and conduction bands that touch near the Fermi level.

Researchers are interested in the possibilities for topological materials in electronics applications such as:

- Ultralow-energy transistors
- Cancer-scanning lasers
- Free-space communication beyond 5G

Topological quantum materials (TQMs) have symmetry-protected band structures with useful electronic properties that have applications in information, sensing, energy and other technologies.

**[More to come ...]**