How do modern helicopters tackle Vortex Ring State?
Helicopter driver here.

I am not aware of any technical features which can prevent it.  Quite simply, the disc must accelerate air downwards to generate lift.  If the helicopter descends into that downward accelerating air, it is recycled through the disc resulting in a catastrophic loss of lift.

The preventative measures are:


Be aware of the flight conditions under which vortex ring state may occur.
Do not fly into these conditions.
Be able to recongise the symptoms of vortex ring state.
Understand, and be practised in, the correct recovery technique, which is most often fly in any direction away from the vortex.


I am not an aerodynamics engineer but I doubt that there is a physical solution to this - and if there was, it would likely have been implemented by now.