Bose–Einstein condensation in an ultra-hot gas of pumped magnons
Bose–Einstein condensation of quasi-particles such as excitons, polaritons, magnons and photons is a fascinating quantum mechanical phenomenon. Unlike the Bose–Einstein condensation of real particles (like atoms), these processes do not require low temperatures, since the high densities of low-energ...
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Published in | Nature communications Vol. 5; no. 1; p. 3452 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
11.03.2014
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | Bose–Einstein condensation of quasi-particles such as excitons, polaritons, magnons and photons is a fascinating quantum mechanical phenomenon. Unlike the Bose–Einstein condensation of real particles (like atoms), these processes do not require low temperatures, since the high densities of low-energy quasi-particles needed for the condensate to form can be produced via external pumping. Here we demonstrate that such a pumping can create remarkably high effective temperatures in a narrow spectral region of the lowest energy states in a magnon gas, resulting in strikingly unexpected transitional dynamics of Bose–Einstein magnon condensate: the density of the condensate increases immediately after the external magnon flow is switched off and initially decreases if it is switched on again. This behaviour finds explanation in a nonlinear ‘evaporative supercooling’ mechanism that couples the low-energy magnons overheated by pumping with all the other thermal magnons, removing the excess heat, and allowing Bose–Einstein condensate formation.
In contrast to real atoms, Bose–Einstein condensation of quasi-particles does not require low temperature, but is obtained via external pumping. Here, the authors show an unexpected transitional dynamics of a Bose–Einstein condensate of magnons due to a nonlinear evaporative supercooling mechanism. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 2041-1723 2041-1723 |
DOI: | 10.1038/ncomms4452 |