Vortex and half-vortex dynamics in a nonlinear spinor quantum fluid

  • L. Dominici, G. Dagvadorj, J. M. Fellows, D. Ballarini, M. De Giorgi, F. M. Marchetti, B. Piccirillo, L. Marrucci, A. Bramati, G. Gigli, M. H. Szymanska, D. Sanvitto
  • Science Advances, December 2015, American Association for the Advancement of Science
  • DOI: 10.1126/sciadv.1500807

Spiraling, splitting and branching dynamics of quantum vortices in a nonlinear polariton fluid

What is it about?

Polariton fluids made of coupled photonic and electronic oscillations have a polarization degree of freedom which can sustain both integer and half-integer quantized vortices. The photonic outcoupling makes possible to track their wavefunction, mapping both the density and phase in time by use of resonant ultrafast imaging.

Why is it important?

Here we could for the first time directly set a polariton condensate carrying either a full or half vortex as initial condition to see their dynamical behavior. We show for the first time the spiraling of an half-vortex, and the branching of FV and HV as vortex lines in a 2D+t domain. We illustrate how the out-of-equilibrium nature of the polariton fluid results in that the vortex trajectories are not driven by intrinsic thermodynamic energy considerations, rather by a kinetic interplay of factors such as the nonlinearity and the disorder background with its associated polarization splitting.

Perspectives

Dr Lorenzo Dominici
CNR NANOTEC, Institute of Nanotechnology

Vortices in a quantum fluid must have an integer winding of the phase. On the one hand this work highlights the driving terms for the rich phenomenology of vortex dynamics in the nonlinear polariton fluid. This is consisting of spiraling, joint path, splitting and also the systematic couple generation of secondary vortices, always preserving the angular momentum. On the other hand, it is noteworthy how the vortex cores exhibit phase singularities which are both point-like and quantized. Hence there is a possible interesting analogy with elementary particles and their reactions such as merging and splitting, couple generation and annihilation. In this sense, such reactions are not driven by the localized particles 'per-sé', rather by the surrounding field due to the nonlinear fluid density, with the possible association of the background disorder to field fluctuations. The 2D+t trajectories of the vortex cores in the two-dimensional polariton fluid represent topological strings which will in the future highlight more complex structures such as closed loops or knots and help understanding the nature of cosmological- or subatomic-scale topology physics.

Read Publication

http://dx.doi.org/10.1126/sciadv.1500807

The following have contributed to this page: Dr Lorenzo Dominici