Superluminal X-waves in a polariton quantum fluid

Antonio Gianfrate , Lorenzo Dominici , Oksana Voronych , Michał Matuszewski , Magdalena Stobińska , Dario Ballarini , Milena De Giorgi , Giuseppe Gigli , Daniele Sanvitto


In this work, we experimentally demonstrate for the first time the spontaneous generation of two-dimensional exciton-polariton X-waves. X-waves belong to the family of localized packets that can sustain their shape without spreading, even in the linear regime. This allows the wavepacket to maintain its shape and size for very low densities and very long times compared to soliton waves, which always necessitate a nonlinearity to compensate the diffusion. Here, we exploit the polariton nonlinearity and uniquely structured dispersion, comprising both positive- and negative-mass curvatures, to trigger an asymmetric four-wave mixing in momentum space. This ultimately enables the self-formation of a spatial X-wave front. Using ultrafast imaging experiments, we observe the early reshaping of the initial Gaussian packet into the X-pulse and its propagation, even for vanishingly small densities. This allows us to outline the crucial effects and parameters that drive the phenomena and to tune the degree of superluminal propagation, which we found to be in close agreement with numerical simulations.
Author Antonio Gianfrate
Antonio Gianfrate,,
, Lorenzo Dominici
Lorenzo Dominici,,
, Oksana Voronych IFTiA
Oksana Voronych ,,
- Institute of Theoretical Physics and Astrophysics
, Michał Matuszewski
Michał Matuszewski,,
, Magdalena Stobińska
Magdalena Stobińska,,
, Dario Ballarini
Dario Ballarini,,
, Milena De Giorgi
Milena De Giorgi,,
, Giuseppe Gigli
Giuseppe Gigli,,
, Daniele Sanvitto
Daniele Sanvitto,,
Journal seriesLight-Science & Applications, ISSN 2047-7538
Issue year2018
Publication size in sheets0.5
Keywords in Englishnegative mass, nonlinearity, polaritons, superluminal, X-waves
Languageen angielski
LicenseJournal (articles only); published final; Uznanie Autorstwa - Użycie Niekomercyjne - Bez utworów zależnych (CC-BY-NC-ND); with publication
Score (nominal)50
ScoreMinisterial score = 50.0, 09-04-2018, ArticleFromJournal
Ministerial score (2013-2016) = 50.0, 09-04-2018, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 14.098 (2) - 2016=14.567 (5)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.