title: Observation of half-quantum vortices in an exciton-polariton condensate.
abstract: Singly quantized vortices have already been observed in many systems, including the superfluid helium, Bose-Einstein condensates of dilute atomic gases, and condensates of exciton-polaritons in the solid state. Two-dimensional superfluids carrying spin are expected to demonstrate a different type of elementary excitations referred to as half-quantum vortices, characterized by a pi rotation of the phase and a pi rotation of the polarization vector when circumventing the vortex core. We detect half-quantum vortices in an exciton-polariton condensate by means of polarization-resolved interferometry, real-space spectroscopy, and phase imaging. Half-quantum vortices coexist with single-quantum vortices in our sample.
authors: Institut de Photique et d'Electronique Quantique (IPEQ), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. konstantinos.lagoudakis@epfl.ch
authors: K G
authors: KG
authors: Lagoudakis
authors: T
authors: T
authors: Ostatnický
authors: A V
authors: AV
authors: Kavokin
authors: Y G
authors: YG
authors: Rubo
authors: R
authors: R
authors: André
authors: B
authors: B
authors: Deveaud-Plédran