Observation of Half-Quantum Vortices in an Exciton-Polariton Condensate
K. G. Lagoudakis,1,*
T. Ostatnick
,2
A. V. Kavokin,2,3
Y. G. Rubo,4
R. André,5
B. Deveaud-Plédran1
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
rotation
of the phase and a
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.
2 School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
3 Marie-Curie Chair of Excellence, University of Rome II, Via della Ricerca Scientifica 1, 00133 Rome, Italy.
4 Centro de Investigación en Energía, Universidad Nacional Autónoma de México, Temixco, 62580 Morelos, Mexico.
5 Institut Néel, Centre National de la Recherche Scientifique (CNRS), 38042 Grenoble, France.
* To whom correspondence should be addressed. E-mail: konstantinos.lagoudakis{at}epfl.ch
