BEGIN:VCALENDAR VERSION:2.0 PRODID:-//wp-events-plugin.com//6.4.7.2//EN TZID:Europe/Paris X-WR-TIMEZONE:Europe/Paris BEGIN:VEVENT UID:1-482@lptms.universite-paris-saclay.fr DTSTART:20170117T110000Z DTEND:20170117T120000Z DTSTAMP:20161213T084245Z URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm s-simon-pigeon/ SUMMARY:Séminaire du LPTMS: Simon Pigeon - LPTMS\, salle 201\, 2ème étag e\, Bât 100\, Campus d'Orsay - 17 Jan 17 11:00 DESCRIPTION:Controlling superfluid vortices in polariton fluids\nSimon Pige on (LKB\, Université Pierre et Marie Curie\, Paris)\nExciton-polaritons\, microcavity half-matter half-light quasi-particles\,  when resonantly dr iven exhibit a superfluid regime. Accordingly\,  topological excitations similar to those predicted in equilibrium  superfluids may spontaneously appear. However\, the non-equilibrium  nature of polaritons requires the system to be continuously pumped in  order to compensate for losses. This driving plays a key role in the  formation and dynamics of such topologi cal excitations. Excited through  a resonant pumping\, the coherent field driving the system imposes a  phase on the polariton fluid which inhibit s the formation of vortices or  solitons. This unique feature of coherent ly driven polariton superfluids  has been used to trap vortices. To that purpose an engineered pumping  profile\, alternating between spatial driv en and non driven regions was  proposed and successfully implemented.\n\n Based on this same idea of spatially engineered pumping profils\, many  w orks done lately focused spontaneous formation of vortices in polariton  superfluids. For practical experimental reasons\, such as high speeds\,  small propagation length and a short lifetimes\, the hydrodynamics of  th ese vortices propagating were largely ignored.\n\nI will present a recent investigation of an optical method allowing us  to overcome these difficu lties\, together with giving the unique  opportunity to directly control and manipulate the properties of the  vortices. The general idea is to su stain the superfluid polariton flow\,  something which generally does not last long outside the excitation  region\, with a secondary supporting e xcitation of low intensity. This  way the flow may propagate over a much longer distance. The vortices  formed in the superfluid are still permitt ed due to the weakness of the  support pump. This allows their propagatio n along large distances and  the observation of their hydrodynamic behavi our. However\, the secondary  coherent driving acting as a support\, allo ws for some other rich and  unique features. At the same time as increasi ng the propagation length\,  the same support driving gives direct contro l over the vortex-antivortex  pair properties\, offering a unique opportu nity to manipulate vortex  locally and accurately.\n\nThe new approach pr oposed allows for the observation of hydrodynamic  behaviour of superflui d vortices\, and initiates a new step regarding the  control of such fund amental entities\, thus paving the way toward their  practical use.\n\nRe ferences:\n\n S. Pigeon\, I. Carusotto\, and C. Ciuti\, Hydrodynamic nucle ation of vortices and solitons in a resonantly excited polariton superflui d\, Phys. Rev. B 83\, 144513 (2011)\n A. Amo\, S. Pigeon\, et al\, Polarit on Superfluids Reveal Quantum Hydrodynamic Solitons\, Science 332\, 1167-1 170 (2011)\n D. Sanvitto\, S. Pigeon\, et al\, All-optical control of the quantum flow of a polariton superfluid\, Nature Photonics 5\, 610-614 (201 1)\n CATEGORIES:seminars LOCATION:LPTMS\, salle 201\, 2ème étage\, Bât 100\, Campus d'Orsay\, 15 Rue Georges Clemenceau\, Orsay\, 91405\, France GEO:48.698185;2.181768 X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\, Orsay\, 91405\, France;X-APPLE-RADIUS=100;X-TITLE=LPTMS\, salle 201\, 2è me étage\, Bât 100\, Campus d'Orsay:geo:48.698185,2.181768 END:VEVENT END:VCALENDAR