Cargando…

The Role of Spin-Flip Collisions in a Dark-Exciton Condensate

We show that a Bose–Einstein condensate consisting of dark excitons forms in GaAs coupled quantum wells at low temperatures. We find that the condensate extends over hundreds of micrometers, well beyond the optical excitation region, and is limited only by the boundaries of the mesa. We show that th...

Descripción completa

Detalles Bibliográficos
Autores principales: Misra, Subhradeep, Stern, Michael, Umansky, Vladimir, Bar-Joseph, Israel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9371640/
https://www.ncbi.nlm.nih.gov/pubmed/35921437
http://dx.doi.org/10.1073/pnas.2203531119
_version_ 1784767199931531264
author Misra, Subhradeep
Stern, Michael
Umansky, Vladimir
Bar-Joseph, Israel
author_facet Misra, Subhradeep
Stern, Michael
Umansky, Vladimir
Bar-Joseph, Israel
author_sort Misra, Subhradeep
collection PubMed
description We show that a Bose–Einstein condensate consisting of dark excitons forms in GaAs coupled quantum wells at low temperatures. We find that the condensate extends over hundreds of micrometers, well beyond the optical excitation region, and is limited only by the boundaries of the mesa. We show that the condensate density is determined by spin-flipping collisions among the excitons, which convert dark excitons into bright ones. The suppression of this process at low temperature yields a density buildup, manifested as a temperature-dependent blueshift of the exciton emission line. Measurements under an in-plane magnetic field allow us to preferentially modify the bright exciton density and determine their role in the system dynamics. We find that their interaction with the condensate leads to its depletion. We present a simple rate-equations model, which well reproduces the observed temperature, power, and magnetic-field dependence of the exciton density.
format Online
Article
Text
id pubmed-9371640
institution National Center for Biotechnology Information
language English
publishDate 2022
publisher National Academy of Sciences
record_format MEDLINE/PubMed
spelling pubmed-93716402023-02-03 The Role of Spin-Flip Collisions in a Dark-Exciton Condensate Misra, Subhradeep Stern, Michael Umansky, Vladimir Bar-Joseph, Israel Proc Natl Acad Sci U S A Physical Sciences We show that a Bose–Einstein condensate consisting of dark excitons forms in GaAs coupled quantum wells at low temperatures. We find that the condensate extends over hundreds of micrometers, well beyond the optical excitation region, and is limited only by the boundaries of the mesa. We show that the condensate density is determined by spin-flipping collisions among the excitons, which convert dark excitons into bright ones. The suppression of this process at low temperature yields a density buildup, manifested as a temperature-dependent blueshift of the exciton emission line. Measurements under an in-plane magnetic field allow us to preferentially modify the bright exciton density and determine their role in the system dynamics. We find that their interaction with the condensate leads to its depletion. We present a simple rate-equations model, which well reproduces the observed temperature, power, and magnetic-field dependence of the exciton density. National Academy of Sciences 2022-08-03 2022-08-09 /pmc/articles/PMC9371640/ /pubmed/35921437 http://dx.doi.org/10.1073/pnas.2203531119 Text en Copyright © 2022 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Physical Sciences
Misra, Subhradeep
Stern, Michael
Umansky, Vladimir
Bar-Joseph, Israel
The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title_full The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title_fullStr The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title_full_unstemmed The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title_short The Role of Spin-Flip Collisions in a Dark-Exciton Condensate
title_sort role of spin-flip collisions in a dark-exciton condensate
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9371640/
https://www.ncbi.nlm.nih.gov/pubmed/35921437
http://dx.doi.org/10.1073/pnas.2203531119
work_keys_str_mv AT misrasubhradeep theroleofspinflipcollisionsinadarkexcitoncondensate
AT sternmichael theroleofspinflipcollisionsinadarkexcitoncondensate
AT umanskyvladimir theroleofspinflipcollisionsinadarkexcitoncondensate
AT barjosephisrael theroleofspinflipcollisionsinadarkexcitoncondensate
AT misrasubhradeep roleofspinflipcollisionsinadarkexcitoncondensate
AT sternmichael roleofspinflipcollisionsinadarkexcitoncondensate
AT umanskyvladimir roleofspinflipcollisionsinadarkexcitoncondensate
AT barjosephisrael roleofspinflipcollisionsinadarkexcitoncondensate