Comment by westurner

[Fractional] Quantum Hall Effect: https://news.ycombinator.com/item?id=39384522 :

> In 1988, it was proposed that there was quantum Hall effect without Landau levels. [3] This quantum Hall effect is referred to as the quantum anomalous Hall (QAH) effect. There is also a new concept of the quantum spin Hall effect which is an analogue of the quantum Hall effect, where spin currents flow instead of charge currents. [4]

How are spin currents and vorticity in electron vortices related?