Observation of Half Quantum Vortices in an Exciton-Polariton Condensate

TL;DR

This paper reports the experimental observation of half quantum vortices in an exciton-polariton condensate, revealing new elementary excitations in spinor superfluids through advanced polarization and phase imaging techniques.

Contribution

First experimental detection of half quantum vortices in an exciton-polariton condensate using polarization resolved interferometry and phase imaging.

Findings

Half quantum vortices coexist with single quantum vortices.

Detection achieved through polarization resolved interferometry.

Observation confirms theoretical predictions of spinor superfluid excitations.

Abstract

Singly quantized vortices have been already 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.