Dynamical formation of a strongly correlated dark condensate of dipolar excitons

Strongly interacting bosons display a rich variety of quantum phases, the study of which has so far been focused in the dilute regime, at a fixed number of particles. Here we demonstrate the formation of a dense Bose–Einstein condensate in a long-lived dark spin state of 2D dipolar excitons. A dark...

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Bibliographic Details
Published in:	Proceedings of the National Academy of Sciences - PNAS Vol. 116; no. 37; pp. 18328 - 18333
Main Authors:	Mazuz-Harpaz, Yotam, Cohen, Kobi, Leveson, Michael, West, Ken, Pfeiffer, Loren, Khodas, Maxim, Rapaport, Ronen
Format:	Journal Article
Language:	English
Published:	United States National Academy of Sciences 10-09-2019
Subjects:	Bose-Einstein condensates Bosons Brightening Dependence Dipole interactions Excitons Physical Sciences Bose–Einstein condensation quantum dipolar gases indirect excitons
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Summary:	Strongly interacting bosons display a rich variety of quantum phases, the study of which has so far been focused in the dilute regime, at a fixed number of particles. Here we demonstrate the formation of a dense Bose–Einstein condensate in a long-lived dark spin state of 2D dipolar excitons. A dark condensate of weakly interacting excitons is very fragile, being unstable against a coherent coupling of dark and bright spin states. Remarkably, we find that strong dipole–dipole interactions stabilize the dark condensate. As a result, the dark phase persists up to densities high enough for a dark quantum liquid to form. The striking experimental observation of a step-like dependence of the exciton density on the pump power is reproduced quantitatively by a model describing the nonequilibrium dynamics of driven coupled dark and bright condensates. This unique behavior marks a dynamical condensation to dark states with lifetimes as long as a millisecond, followed by a brightening transition at high densities.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Edited by Shaul Mukamel, University of California, Irvine, CA, and approved August 1, 2019 (received for review February 27, 2019) Author contributions: Y.M.-H. and K.C. performed the experiments; Y.M.-H., M.L., M.K., and R.R. developed the theory; Y.M.-H. and K.C. analyzed data; K.W. and L.P. grew the samples; and Y.M.-H., M.K., and R.R. wrote the paper.
ISSN:	0027-8424 1091-6490
DOI:	10.1073/pnas.1903374116