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Updated: Jun 18, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Observation of half-quantum vortices in an exciton-polariton condensate
K G Lagoudakis1, T Ostatnický, A V Kavokin
1Institut de Photique et d'Electronique Quantique (IPEQ), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. konstantinos.lagoudakis@epfl.ch
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.
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