Quantum matter

As quantum matter is called many-body systems whose macroscopic properties are determined by phenomena in quantum physics. Research topics in the field of quantum matter can be found in solid-state physics and chemistry ( quantum materials ), in atomic physics (ultra-cold atomic gases) and in astrophysics ( white dwarfs and neutron stars ). The quantum particles can either be fermions (e.g. electrons , nucleons , quarks ) or bosons (e.g. bosonic atoms).

Fermionic quantum matter

A ferromagnet levitates over a superconductor. Both materials are in a macroscopic quantum state and can therefore be referred to as quantum matter.

Electrons in solids and in white dwarfs are quantum-mechanically degenerate and contribute to the stability of the respective overall system through their degeneracy pressure. The same is true of neutrons and protons in neutron stars. At sufficiently low temperatures, degenerate fermion systems show a multitude of macroscopic quantum phenomena such as B. magnetism , superconductivity and topological edge channels in quantum materials and superfluidity of ³ He atoms . In neutron stars there are also clues for macroscopic quantum states, in particular neutron superfluidity and proton superconductivity. Under extreme conditions (especially inside neutron stars and with high-energy collisions of heavy ions in particle accelerators) a quark-gluon plasma is created , for which a superconducting state of free quarks ( color superconductivity ) has been predicted. However, this has not yet been clearly proven.

The Bose condensation of a cold atomic gas made up of rubidium atoms .

Bosonic quantum matter

In bosonic many-body systems, too, a macroscopic quantum state is created by Bose condensation at low temperatures . The best-known example is the superfluid state of ⁴ He atoms. Bose condensates can also be created by cooling gases from bosonic atoms. In solids, the condensation of bosonic quasiparticles such as B. magnons and excitons detected.

Individual evidence

^ B. Keimer , JE Moore: The physics of quantum materials . In: Nature Physics . tape 13 , no. 11 , October 30, 2017, ISSN 1745-2473 , p. 1045-1055 , doi : 10.1038 / nphys4302 ( nature.com [accessed October 21, 2018]).
↑ Superfluidity and Superconductivity in Neutron Stars | NewCompStar. Retrieved October 22, 2018 (American English).
^ The Nobel Prize in Physics 2001. Retrieved October 21, 2018 (American English).
↑ SO Demokritov, VE Demidov, O. Dzyapko, GA Melkov, AA Serga: Bose-Einstein condensation of quasi-equilibrium magnons at room temperature under pumping . In: Nature . tape 443 , no. 7110 , September 2006, ISSN 0028-0836 , p. 430–433 , doi : 10.1038 / nature05117 ( nature.com [accessed October 21, 2018]).
^ J. Kasprzak, M. Richard, S. Kundermann, A. Baas, P. Jeambrun: Bose-Einstein condensation of exciton polaritons . In: Nature . tape 443 , no. 7110 , September 2006, ISSN 0028-0836 , p. 409-414 , doi : 10.1038 / nature05131 ( nature.com [accessed October 21, 2018]).

[1] B. Keimer , JE Moore: The physics of quantum materials . In: Nature Physics . tape 13 , no. 11 , October 30, 2017, ISSN 1745-2473 , p. 1045-1055 , doi : 10.1038 / nphys4302 ( nature.com [accessed October 21, 2018]).

[2] Superfluidity and Superconductivity in Neutron Stars | NewCompStar. Retrieved October 22, 2018 (American English).

[3] The Nobel Prize in Physics 2001. Retrieved October 21, 2018 (American English).

[4] SO Demokritov, VE Demidov, O. Dzyapko, GA Melkov, AA Serga: Bose-Einstein condensation of quasi-equilibrium magnons at room temperature under pumping . In: Nature . tape 443 , no. 7110 , September 2006, ISSN 0028-0836 , p. 430–433 , doi : 10.1038 / nature05117 ( nature.com [accessed October 21, 2018]).

[5] J. Kasprzak, M. Richard, S. Kundermann, A. Baas, P. Jeambrun: Bose-Einstein condensation of exciton polaritons . In: Nature . tape 443 , no. 7110 , September 2006, ISSN 0028-0836 , p. 409-414 , doi : 10.1038 / nature05131 ( nature.com [accessed October 21, 2018]).