Dynamics of a Vortex Lattice in an Expanding Polariton Quantum Fluid

If a quantum fluid is driven with enough angular momentum, at equilibrium the ground state of the system is given by a lattice of quantized vortices whose density is prescribed by the quantization of circulation. We report on the first experimental study of the Feynman-Onsager relation in a nonequilibrium polariton fluid, free to expand and rotate. Upon initially imprinting a lattice of vortices in the quantum fluid, we track the vortex core positions on picosecond timescales. We observe an accelerated stretching of the lattice and an outward bending of the linear trajectories of the vortices, due to the repulsive polariton interactions. Access to the full density and phase fields allows us to detect a small deviation from the Feynman-Onsager rule in terms of a transverse velocity component, due to the density gradient of the fluid envelope acting on the vortex lattice.

Automated summary

The study investigates the behavior of a lattice of vortices in a nonequilibrium polariton fluid, revealing accelerated stretching and outward bending of the lattice and vortex trajectories due to repulsive interactions. Access to full density and phase fields allows detection of a small deviation from the Feynman-Onsager rule in terms of a transverse velocity component caused by the density gradient of the fluid envelope acting on the vortex lattice.