SUPERFLUIDITY and QUANTIZED VORTICES
(youtube link1 + youtube link2)
One of the intriguing properties of superfluidity is the possibility to have quantized vortices states. Since the bosonic fluid has got its own wavefunction with an amplitude and phase, in order for a vortex to be a quasi-stable state or solution, it must reconnect with itself when performing a loop around the central "phase singularity". Akin an atomic orbital is quantized since the electron phase must be reconnected with itself, so the phase of the fluid must overtake one, two, three or more discrete 2π turns when rotating around the vortex core. Here aside it is illustrated a double polariton vortex coherently excited by a picosecond laser vorticant pulse in a 120x120 micron area of the device and then left free to evolve. It keeps rotating for tens of thousands optical loops before being washed away by nonlinear polaritonic interactions and evaporating out due to photon leakage dissipations.
Here below the amplitude and phase of the two spin components in an half-vortex state are represented, together with the 2D+t spiraling dynamics of the phase singularity in a weakly nonlinear regime (reelaboration from data of the paper Science Advances 1, e1500807, 2015 )