Comment on « Linear wave dynamics explains observations attributed to dark-solitons in a polariton quantum fluid »

A. Amo 1 J. Bloch 1 A. Bramati 2 I. Carusotto 3 C. Ciuti 4 B. Deveaud-Plédran 5 E. Giacobino 2 G. Grosso 6 A. Kamchatnov 7 Guillaume Malpuech 8 N. Pavloff 9 S. Pigeon 10 D. Sanvitto 11 D. D. Solnyshkov 8

Physical Review Letters, American Physical Society, 2015, 115, pp.089401

In a recent preprint (arXiv:1401.1128v1) Cilibrizzi and co-workers report experiments and simulations showing the scattering of polaritons against a localised obstacle in a semiconductor microcavity. The authors observe in the linear excitation regime the formation of density and phase patterns reminiscent of those expected in the non-linear regime from the nucleation of dark solitons. Based on this observation, they conclude that previous theoretical and experimental reports on dark solitons in a polariton system should be revised. Here we comment why the results from Cilibrizzi et al. take place in a very different regime than previous investigations on dark soliton nucleation and do not reproduce all the signatures of its rich nonlinear phenomenology. First of all, Cilibrizzi et al. consider a particular type of radial excitation that strongly determines the observed patterns, while in previous reports the excitation has a plane-wave profile. Most importantly, the nonlinear relation between phase jump, soliton width and fluid velocity, and the existence of a critical velocity with the time-dependent formation of vortex-antivortex pairs are absent in the linear regime. In previous reports about dark soliton and half-dark soliton nucleation in a polariton fluid, the distinctive dark soliton physics is supported both by theory (analytical and numerical) and experiments (both continuous wave and pulsed excitation).

  • 1. LPN - Laboratoire de photonique et de nanostructures
  • 2. LKB (Jussieu) - Laboratoire Kastler Brossel
  • 3. INO-CNR BEC Center and Dipartimento di Fisica
  • 4. MPQ - Matériaux et Phénomènes Quantiques
  • 5. EPFL - Ecole Polytechnique Fédérale de Lausanne
  • 6. Massachusetts Institute of Technology
  • 7. Institute of Spectroscopy
  • 8. Institut Pascal [Aubiere]
  • 9. LPTMS - Laboratoire de Physique Théorique et Modèles Statistiques
  • 10. Queen's University Belfast [Belfast]
  • 11. ISAC-CNR - ISAC-CNR Lecce Section