Topological order and thermal equilibrium in polariton condensates
Sanchez Munoz, Carlos
De Giorgi, Milena
Pfeiffer, Loren N.
Laussy, Fabrice P.
Szymanska, Marzena H.
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AbstractWe report the observation of the Berezinskii-Kosterlitz-Thouless transition for a 2D gas of exciton-polaritons, and through the joint measurement of the first-order coherence both in space and time we bring compelling evidence of a thermodynamic equilibrium phase transition in an otherwise open driven/dissipative system. This is made possible thanks to long polariton lifetimes in high-quality samples with small disorder and in a reservoir-free region far away from the excitation spot, that allow topological ordering to prevail. The observed quasi-ordered phase, characteristic for an equilibrium 2D bosonic gas, with a decay of coherence in both spatial and temporal domains with the same algebraic exponent, is reproduced with numerical solutions of stochastic dynamics, proving that the mechanism of pairing of the topological defects (vortices) is responsible for the transition to the algebraic order. Finally, measurements in the weak-coupling regime confirm that polariton condensates are fundamentally different from photon lasers and constitute genuine quantum degenerate macroscopic states.
CitationCaputo D., Ballarini D., Dagvadorj G., Sánchez Muñoz C., De Giorgi M., Dominici L., West K., Pfeiffer LN., Gigli G., Laussy FP., Szymańska MH., Sanvitto D. (2018) Topological order and equilibrium in polariton condensates, Nature Materials, 17(2) pp. 145-151. doi: 10.1038/nmat5039
PublisherNature publishing group
DescriptionThis is an accepted manuscript of an article published by Nature publishing group in Nature Materials on 04/12/2017 available online: https://doi.org/10.1038/nmat5039 The accepted version of the publication may differ from the final published version.
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