Bose-Einstein Condensation of Quasi-Particles by Rapid Cooling

M. Schneider; T. Brächer; D. Breitbach; V. Lauer; P. Pirro; D. A. Bozhko; A. A. Serga; H. Yu. Musiienko-Shmarova; B. Heinz; Q. Wang; T. Meyer; F. Heussner; S. Keller; E. Th. Papaioannou; B. Lägel; T. Löber; V. S. Tiberkevich; A. N. Slavin; C. Dubs; B. Hillebrands; A. V. Chumak

doi:10.1038/s41565-020-0671-z

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arXiv · 1612.07305

Bose-Einstein Condensation of Quasi-Particles by Rapid Cooling

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Abstract

The fundamental phenomenon of Bose-Einstein Condensation (BEC) has been observed in different systems of real and quasi-particles. The condensation of real particles is achieved through a major reduction in temperature while for quasi-particles a mechanism of external injection of bosons by irradiation is required. Here, we present a novel and universal approach to enable BEC of quasi-particles and to corroborate it experimentally by using magnons as the Bose-particle model system. The critical point to this approach is the introduction of a disequilibrium of magnons with the phonon bath. After heating to an elevated temperature, a sudden decrease in the temperature of the phonons, which is approximately instant on the time scales of the magnon system, results in a large excess of incoherent magnons. The consequent spectral redistribution of these magnons triggers the Bose-Einstein condensation.

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M. Schneider, T. Brächer, D. Breitbach, V. Lauer, P. Pirro, D. A. Bozhko, A. A. Serga, H. Yu. Musiienko-Shmarova, B. Heinz, Q. Wang, T. Meyer, F. Heussner, S. Keller, E. Th. Papaioannou, B. Lägel, T. Löber, V. S. Tiberkevich, A. N. Slavin, C. Dubs, B. Hillebrands, A. V. Chumak. 2016-12-21. Bose-Einstein Condensation of Quasi-Particles by Rapid Cooling. https://doi.org/10.1038/s41565-020-0671-z

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