Séminaire du LPTMS: Maxime Richard



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One dimensional polariton condensate in semiconductor microstructure

Maxime Richard, Institut Néel

In semiconductor nanostructures like microcavities, when the so-called exciton-photon strong coupling regime is reached, the proper eigenstates of the system are mixed exciton-photon states called exciton-polaritons. This last decade, 2-dimensional microcavity exciton-polaritons in the quantum degenerate regime have shown fascinating properties e.g. polariton lasing, Bose-Einstein condensation and superfluidity [1]. Recently, new systems and new geometries are being developed in order to study the polariton physics of dimensionality D

Recently, new systems in the strong coupling regime like ZnO microwires have been introduced [4]. We show that polaritons in these systems have unusual characteristics: they have only one spatial degree of freedom and they exhibit low thermal decoherence thanks to a large Rabi splitting. Furthermore, they are robust at large density and high temperature owing to the large exciton binding energy of ZnO. Striking differences exist also in the condensate phase. At cryogenic temperature and under strong pulsed optical excitation, a transient polariton condensate is formed by stimulated relaxation into a state with a 97% excitonic fraction, i.e. with a mass 15 times heavier than for polaritons usually encountered in planar microcavities. This feature is enabled by the combination of a large Rabi splitting (300 meV) and a very small inhomogeneous broadening of excitons (~1 meV).

[1] L.S. Dang et al. Phys. Rev. Lett. 81 3920 (1998) ; J. Kasprzak et al., Nature 443, 409 (2006) ; A. Amo et al., Nat. Phys. 5, 805 (2009).
[2] E. Wertz et al., Nat. Phys. 6, 840-864 (2010).
[3] G. Christmann et al. Appl. Phys. Lett. 93, 051102 (2008).
[4] L. Sun et al, Phys. Rev. Letters 100, 156403 (2008); A. Trichet et al., Phys. Rev. B 83, 041302R (2011)

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